IL-1 receptor based cytokine traps and method of using

ABSTRACT

The present invention provides a fusion polypeptide capable of binding interleukin-1 (O:-1) to form a nonfunctional complex. It also provides a nucleic acid sequence encoding the fusion polypeptide and methods of using the fusion polypeptide.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 10/282,162 filed 28Oct. 2002, now U.S. Pat. No. 6,927,044, which is a continuation-in-partof U.S. Ser. No. 09/787,835, filed 22 Mar. 2001, now abandoned, which isa U.S. National Stage Application of International Application No.PCT/US99/22045, filed 22 Sep. 1999, which is a continuation of U.S. Ser.No. 09/313,942, filed 19 May 1999, now U.S. Pat. No. 6,472,179, whichclaims the benefit under 35 U.S.C. § 119(e) of U.S. ProvisionalApplication No. 60/101,858 filed Sep. 25, 1998. The disclosures of thesepublications are hereby incorporated by reference into this applicationin their entireties.

FIELD OF THE INVENTION

The invention relates to receptor-based fusion proteins capable ofbinding and inhibiting the biological activity of a cytokine. Morespecifically, the invention relates to interleukin-1 (IL-1) fusionproteins capable of trapping and inhibiting the action of IL-1, andtherapeutic uses thereof.

DESCRIPTION OF RELATED ART

Although discovered for varying biological activities, ciliaryneurotrophic factor (CNTF), leukemia inhibitory factor (LIF), oncostatinM (OSM) and interleukin-6 (IL-6) comprise a defined family of cytokines(referred to herein as the “CNTF family” of cytokines). These cytokinesare grouped together because of their distant structural similarities(Bazan et al. 1991 J. Neuron 7:197-208), and, perhaps more importantly,because they share “β” signal-transducing receptor components (Baumannet al. 1993 J. Biol. Chem. 265:19853-19862); Davis et al. 1993 Science260:1805-1808; Gearing et al. 1992 Science 255:1434-1437; Ip et al. 1992Cell 69: 1121-1132; Stahl et al. 1993 J. Biol. Chem. 268: 7628-7631;Stahl et al. 1993 Cell 74:587-590). Receptor activation by this familyof cytokines results from either homo- or hetero-dimerization of these βcomponents.

In addition to the β components, some of these cytokines also requirespecificity-determining “α” components that are more limited in theirtissue distribution than the β components, and thus determine thecellular targets of the particular cytokines. Thus, LIF and OSM arebroadly acting factors that may only require the presence of gp130 andLIFRβ on responding cells, while CNTF requires CNTFRα. Both CNTFRα andIL-6Rα (Hibi et al. Cell 63:1149-1157) can function as soluble proteins,consistent with the notion that they do not interact with intracellularsignaling molecules but that they serve to help their ligands interactwith the appropriate signal transducing β subunits.

Additional evidence from other cytokine systems also supports the notionthat dimerization provides a common mechanism by which all cytokinereceptors initiate signal transduction. Studies with the erythropoietin(EPO) receptor are also consistent with the importance of dimerizationin receptor activation, as EPO receptors can be constitutively activatedby a single amino acid change that introduces a cysteine residue andresults in disulfide-linked homodimers (Watowich et al. 1992 Proc. Natl.Acad. Sci. USA 89:2140-2144).

In addition to homo- or hetero-dimerization of β subunits as thecritical step for receptor activation, a second important feature isthat formation of the final receptor complex by the CNTF family ofcytokines occurs through a mechanism whereby the ligand successivelybinds to receptor components in an ordered manner (Davis et al. 1993supra). Thus CNTF first binds to CNTFRα, forming a complex which thenbinds gp130 to form an intermediate (called here the αβ1 intermediate)that is not signaling competent because it has only a single βcomponent, before finally recruiting LIFRβ to form a heterodimer of βcomponents which then initiates signal transduction. Altogether, thesefindings led to a proposal for the structure of a generic cytokinereceptor complex in which each cytokine can have up to 3 receptorbinding sites: a site that binds to an optional aspecificity-determining component (a site), a site that binds to thefirst β signal-transducing component (β1 site), and a site that binds tothe second β signal-transducing component (β2 site). These 3 sites areused in sequential fashion, with the last step in complexformation—resulting in β component dimerization—critical for initiatingsignal transduction (Davis et al. 1993 supra). Knowledge of the detailsof receptor activation and the existence of the non-functional β1intermediate for CNTF has led to the finding that CNTF is a highaffinity antagonist for IL-6 under certain circumstances, and providesthe strategic basis for designing ligand or receptor-based antagonistsfor the CNTF family of cytokines as detailed below.

BRIEF SUMMARY OF THE INVENTION

An object of the invention is the construction of several specificinterleukin-1 (IL-1) cytokine antagonists, termed “IL-1 Traps”, eachhaving different sequences but all being capable of blocking the bindingof IL-1 to its receptor, thus functioning as IL-1 antagonists.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1: Ordered binding of receptor components in a model of a genericcytokine receptor. The model indicates that cytokines contain up to 3receptor binding sites and interact with their receptor components bybinding first the optional a component, followed by binding to b1, andthen b2. The b components for many cytokine receptors interact throughmembrane proximal regions (shaded boxes) with the Jak/Tyk family ofcytoplasmic protein tyrosine kinases. Only upon dimerization of bcomponents is signal transduction initiated, as schematized by thetyrosine phosphorylations (P) of the b components and the Jak/Tykkinases.

FIG. 2: CNTF inhibits IL-6 responses in a PC12 cell line (called PC12D)that expresses IL6Ra, gp130, CNTFRa, but not LIFRb. Serum-deprived PC12Dcells were incubated +IL-6 (50 ng/mL) in the presence or absence of CNTFas indicated. Some plates also received soluble IL6Ra (1 mg/mL) orsoluble CNTFRa (1 mg/mL) as indicated. Cell lysates were subjected toimmunoprecipitation with anti-gp130 and immunoblotted withanti-phosphotyrosine. Tyrosine phosphorylation of gp130 is indicative ofIL-6 induced activation of the IL-6 receptor system, which is blockedupon coaddition of CNTF.

FIG. 3: Scatchard analysis of iodinated CNTF binding on PC12D cells.PC12D cells were incubated with various concentrations of iodinated CNTFin the presence or absence of excess non-radioactive competitor todetermine the specific binding. The figure shows a Scatchard plot of theamount of iodinated CNTF specifically bound, and gives data consistentwith two binding sites with dissociation constants of 9 pM and 3.4 nM.

FIGS. 4A-4B. The amino acid sequence of human gp130-Fc-His₆ (SEQ ID NO:7). Amino acids 1 to 619 are from human gp130 (Hibi et al., Cell63:1149-1157 (1990). Note that amino acid number 2 has been changed froma Leu to a Val in order to accommodate a Kozak sequence in the codingDNA sequence. The signal peptide of gp130-Fc-His₆ has been italicized(amino acids 1 to 22). The Ser-Gly bridge is shown in bold type (aminoacids 620, 621). Amino acids 662 to 853 are from the Fc domain of humanIgG1 (Lewis, et al., J. Immunol. 151:2829-2838 (1993). (†) mark the twocysteines (amino acids number 632 and 635) of the IgG hinge precedingthe Fc that form the inter-chain disulfide bridges that link two Fcdomains. The hexahistine tag is shown in bold/italic type (amino acids854 to 859). (•) shows the position of the STOP codon.

FIG. 5: The amino acid sequence of human IL-6Ra-Fc (SEQ ID NO: 8). Key:Amino acids 1 to 358 are from human IL-6Ra (Yamasaki et al. 1088 Science241:825-828). Note that amino acid number 2 has been changed from a Leuto a Val in order to accommodate a Kozak sequence in the coding DNAsequence. The signal peptide of IL-6Ra-Fc has been italicized (aminoacids 1 to 19). The Ala-Gly bridge is shown in bold type (amino acids359, 360). Amino acids 361 to 592 are from the Fc domain of human IgG1(Lewis et al., J. Immunol. 151:2829-2838 (1993). (†) mark the twocysteines (amino acids number 371 and 374) of the IgG hinge precedingthe Fc that form the inter-chain disulfide bridges that link two Fcdomains. (•) shows the position of the STOP codon.

FIG. 6: The CNTF/IL-6/IL-11 receptor system. The ordered formation ofthe hexameric signal transducing receptor complex is depictedschematically. The cytokine associates with the Ra component to form anobligatory cytokine•Ra complex (Kd is about 5 nM). This low affinitycomplex next associates with the first signal transducing component,marked b1, to form a high affinity cytokine•Ra•b1 complex (Kd is about10 pM). In the case of IL-6Ra, this component is gp130. This trimerichigh affinity complex subsequently associates with another such complex.Formation of this complex results in signal transduction as it involvesdimerization of two signal transducing components, marked b1 and b2respectively (adapted from (Ward et al., J. Bio. Chem. 269:23286-23289(1994); Stahl and Yancopoulos, J. Neurobiology 25:1454-1466 (1994);Stahl and Yancopoulos, Cell 74:587-590 (1993).

FIG. 7: Design of heterodimeric receptor-based ligand Traps for IL-6.The heterodimeric ligand Trap is comprised of two interdisulfide linkedproteins, gp130-Fc and IL-6Ra-Fc. The gp130-Fc•IL-6Ra-Fc complex (upperpanel) is shown to mimic the high affinity cytokine•Ra•b1 complex (lowerpanel). The ligand Trap functions as an antagonist by sequestering IL-6and thus rendering unavailable to interact with the native receptors onIL-6-responsive cells.

FIG. 8. Heteromeric immunoglobulin Heavy/Light Chain Receptor Fusions.An example of a heavy/light chain receptor fusion molecule isschematically depicted. The extracellular domain of gp130 is fused toCg, whereas the extracellular domain of IL-6Ra is fused to the constantregion of the kappa chain (k). The inter-chain disulfide bridges arealso depicted (S-S).

FIGS. 9A-9B. Amino acid sequence of gp130-Cg1 (SEQ ID NO: 9). Key: Aminoacids 1 to 619 are from human gp130 (Hibi, et al., Cell 63:1149-1157(1990). Ser-Gly bridge is shown in bold type. Amino acids 662 to 651 arefrom the constant region of human IgG1 (Lewis et al., J. Immunol.151:2829-2838 (1993). (*) shows the position of the STOP codon.

FIG. 10: Amino acid sequence of gp130D3fibro (SEQ ID NO: 10). Key: Aminoacids 1 to 330 are from human gp130 (Hibi et al. Cell 63:1149-1157(1990). Other symbols as described in FIG. 9.

FIG. 11: Amino acid sequence of J-CH1 (SEQ ID NO: 11). Key: The Ser-Glybridge is shown in bold, the J-peptide is shown in italics, the C_(H)1domain is underlined.

FIG. 12: Amino acid sequence of Cg4 (SEQ ID NO: 12). Key: The Ser-Glybridge is shown in bold type. Amino acids 2 to 239 comprise the Cg4sequence.

FIG. 13: Amino acid sequence of k-domain (SEQ ID NO: 13). Key: TheSer-Gly bridge is shown in bold type. Amino acids 2 to 108 comprise thek domain. The C-terminal cysteine (amino acid 108) is that involved inthe disulfide bond of the k domain with the C_(H)1 domain of Cg.

FIG. 14: Amino acid sequence of 1-domain (SEQ ID NO: 14). Key: TheSer-Gly bridge is shown in bold type. Amino acids 2 to 106 comprise the1 domain (Cheung, et al., J. Virol. 66: 6714-6720 (1992). The C-terminalcysteine (amino acid 106) is that involved in the disulfide bond of the1 domain with the C_(H)1 domain of Cg.

FIG. 15: Amino acid sequence of the soluble IL-6Ra domain (SEQ ID NO:15). Key: Amino acids 1 to 358 comprise the soluble IL-6Ra domain(Yamasaki, et al., Science 241:825-828 (1988). The Ala-Gly bridge isshown in bold type.

FIG. 16: Amino acid sequence of the soluble IL-6Rα313 domain (SEQ ID NO:16): Key: Amino acids 1 to 313 comprise the truncated IL-6Ra domain(IL-6Ra313). The Thr-Gly bridge is shown in bold type.

FIG. 17: Purification of gp130-Cg1•IL-6Ra-k. 4% to 12% SDS-PAGE gradientgel run under non-reducing conditions. Proteins were visualized bystaining with silver. Lane 1: approximately 100 ng of material purifiedover Protein A Sepharose (Pharmacia). Lane 2: Molecular size standards(Amersham). Lane 3: The Protein A-purified material shown here afterfurther purification over an IL-6 affinity chromatography step. Thepositions of the gp130-Cg1 dimer [(gp130-Cg1)₂], the gp130-Cg1 dimerassociated with one IL-6Ra-k [(gp130-Cg1)₂•(IL-6Ra-k)₁], and thegp130-Cg1 dimer associated with two IL-6Ra-k [(gp130-Cg1)₂•(IL-6Ra-k)₂]are shown, as well as the sizes for the molecular size standards inkilodaltons (200, 100, and 46).

FIG. 18: IL-6 dissociates slowly from the ligand Trap. The dissociationrate of IL-6 from a heavy/light chain receptor-based ligand Trap(gp130-Cg1•IL-6Ra-k) was compared to that obtained with the neutralizingmonoclonal antibody B-E8 (BE8 MAb).

FIGS. 19A-19B: IL-6 can induce multimerization of the ligand Trap. (FIG.19A) Two different ligand Traps are depicted schematically and listedaccording to their ability to bind protein A. gp130-Fc•IL-6Ra-Fc (GF6F)binds protein A via its Fc-domains, whereas gp130—C_(H)1•IL-6Ra-k (G16K)does not bind to protein A. (FIG. 19B) Anti-kappa western blotting ofproteins precipitated with Protein A-Sepharose from mixtures ofGF6F±IL-6, G16K±IL-6, or GF6F plus G16K±IL-6, as marked.

FIG. 20: Inhibition of IL-6-dependent XG-1 cell proliferation. XG-1cells [Zhang, et al., Blood 83:3654-3663 (1994)] were prepared for aproliferation assay by starving the cells from IL-6 for 5 hours. Assayswere set up in 96-well tissue culture dishes in RPMI+10% fetal calfserum+penicillin/streptomycin+0.050 nM 2-mercaptoethanol+glutamine. 0.1ml of that media was used per well. Cells were suspended at a density of250,000 per ml at the start of the assay. 72 hours post addition ofIL-6±ligands Traps or antibodies, an MTT assay was performed asdescribed (Panayotatos et al. Biochemistry 33:5813-5818 (1994). Thedifferent ligand Traps utilized are listed.

FIGS. 21A-21D: Nucleotide sequence (SEQ ID NO: 17) encoding and deducedamino acid sequence (SEQ ID NO: 18) of fusion polypeptide designated 424which is capable of binding the cytokine IL-4 to form a nonfunctionalcomplex.

FIGS. 22A-22D: Nucleotide sequence (SEQ ID NO: 19) encoding and deducedamino acid sequence (SEQ ID NO: 20) of fusion polypeptide designated 603which is capable of binding the cytokine IL-4 to form a nonfunctionalcomplex.

FIGS. 23A-23D: Nucleotide sequence (SEQ ID NO: 21) encoding and deducedamino acid sequence (SEQ ID NO: 22) of fusion polypeptide designated 622which is capable of binding the cytokine IL-4 to form a nonfunctionalcomplex.

FIGS. 24A-24F: Nucleotide sequence (SEQ ID NO: 23) encoding and deducedamino acid sequence (SEQ ID NO: 24) of fusion polypeptide designated 412which is capable of binding the cytokine IL-6 to form a nonfunctionalcomplex.

FIGS. 25A-25F: Nucleotide sequence (SEQ ID NO: 25) encoding and deducedamino acid sequence (SEQ ID NO: 26) of fusion polypeptide designated 616which is capable of binding the cytokine IL-6 to form a nonfunctionalcomplex.

FIGS. 26A-26E: Nucleotide sequence (SEQ ID NO: 27) encoding and deducedamino acid sequence (SEQ ID NO: 28) of fusion polypeptide designated 569which is capable of binding the cytokine IL-1 to form a nonfunctionalcomplex.

FIG. 27: Shows that an IL-4 Trap designated 4SC375, which is a fusionpolypeptide of IL-2Rg-scb-IL4Ra-FcΔC1, is several orders of magnitudebetter as an IL-4 antagonist than IL4RaFcΔC1 alone in the TF1 cellbioassay.

FIG. 28: Shows that an IL-4 Trap designated 4SC375 displays antagonisticactivity in the TF1 cell bioassay equivalent to an IL-4 Trap designated4SC424 (described in FIGS. 21A-21D) which is a fusion polypeptide ofIL-2Rg-IL4Ra-FcΔC1 having the IL-2Rg component flush with the IL-4Racomponent.

FIG. 29: Shows that the IL6 Trap (6SC412 IL6R-scb-gpx-FcΔC1) describedin FIGS. 24A-24F is a better antagonist of IL-6 in the XG1 bioassay thanthe neutralizing monoclonal antibody to human IL-6-BE8.

FIG. 30: Shows that the Trap 1SC569 (described in FIGS. 26A-26E) is ableto antagonize the effects of IL-1 and block the IL-6 production from MRC5 cells upon treatment with IL-1.

FIGS. 31A-31G: The nucleotide (SEQ ID NO: 29) and encoded amino acid(SEQ ID NO: 30) sequence of the IL-4Ra.IL-13Ra1.Fc single chain Trapconstruct is set forth.

FIGS. 32A-32G: The nucleotide (SEQ ID NO: 31) and encoded amino acid(SEQ ID NO: 32) sequence of the IL-13Ra1.IL-4Ra.Fc single chain Trapconstruct is set forth.

FIG. 33: Blocking of IL-13 by IL-4Ra.IL-13Ra1.Fc and IL-13Ra1.IL-4Ra.Fc.Addition of either IL-4Ra.IL-13Ra1.Fc or IL-13Ra1.IL-4Ra.Fc Trap at aconcentration of 10 nM blocks IL-13-induced growth up to ˜2 nM. At anIL-13 concentration of ˜4-5 nM the growth of TF1 cells is inhibited by50%.

FIG. 34: Blocking of IL-4 by IL-4Ra.IL-13Ra1.Fc and IL-13Ra1.IL-4Ra.Fc.Addition of either IL-4Ra.IL-13Ra1.Fc or IL-13Ra1.IL-4Ra.Fc at aconcentration of 10 nM blocks IL-4-induced growth up to ˜1 nM. At anIL-4 concentration of ˜3-4 nM the growth of TF1 cells is inhibited by50%.

FIG. 35: Human IL-1 Trap blocks the in vivo effects of exogenouslyadministered huIL-1. BALB/c mice were given subcutaneous injection ofhuIL-1 (0.3 μg/kg) at time 0. Twenty-four hours prior to huIL-1injection, the animals were pre-treated with either vehicle or 150-foldmolar excess of huIL-1 Trap. Two hours prior to sacrifice (26 hrs), themice were re-challenged with a second injection of huIL-1 (0.3 μg/kg,s.c.). Blood samples were collected at various time points and sera wereassayed for IL-1 levels (expressed as mean+/−SEM; n=5 per group).

FIGS. 36A & 36B: Human IL-4 Trap antagonizes the effects of human IL-4in monkeys. FIG. 36A: Cynomologus monkeys were treated in three parts asindicated. Human IL-4 (25 μg/kg) was injected subcutaneously twice dailyfor 4 days and human IL-4 Trap (8 mg/ml) and vehicle were givenintravenously daily for 5 days, beginning 1 day prior to human IL-4administration. Plasma was collected daily and assayed for MCP-1 levels.Results were expressed as mean +/−SEM; n=4. (ANOVA p<0.0007;Tukey-Kramer: Part 2 vs. Part 1, p, 0.05; Part 2 vs. Part 3, p, 0.05;Part 1 vs. Part 3, not significant.) FIG. 36B: Cynomologus monkeys weretreated in three parts as indicated. Human IL-4 (25 μg/kg) was injectedsubcutaneously twice daily for 4 days and human IL-4 Trap (8 mg/ml) andvehicle were given intravenously daily for 5 days, beginning 1 day priorto human IL-4 administration. Whole blood was collected daily for flowcytometry analysis for CD16. Results were expressed as mean +/−SEM; n=4.(ANOVA p<0.042; Tukey-Kramer: Part 2 vs. Part 1, p<0.05; Part 2 vs. Part3 and Part 1 vs. Part 3, not significant.)

FIG. 37: Murine IL-4 Trap partially prevented IL-4-mediated IgE increasein mice. BALB/C mice injected with anti-mouse IgD (100 μl/mouse, s.c.)were randomly divided into 3 groups, each received (on days 3-5) eithervehicle, murine IL-4 Trap (1 mg/kg, s.c.), or a monoclonal antibody tomouse IL-4 (1 mg/kg, s.c.). Sera were collected at various time pointsand assayed for IgE levels. Results were expressed as mean +/−SEM (n=5per group). (ANOVA p=0.0002; Tukey-Kramer: vehicle vs. IL-4 Trap,p<0.01; vehicle vs. IL-4 antibody, p<0.001; IL-4 Trap vs. IL-4 antibody,not significant).

FIGS. 38A-38I: Nucleotide (SEQ ID NO: 33) and deduced amino acid (SEQ IDNO: 34) sequence of Human IL-1 Trap 570-FE.

FIG. 39A-39I: Nucleotide (SEQ ID NO: 35) and deduced amino acid (SEQ IDNO: 36) sequence of Human IL-1 Trap 570-FE.B.

FIGS. 40A-40I: Nucleotide (SEQ ID NO: 37) and deduced amino acid (SEQ IDNO: 38) sequence of Human IL-1 Trap 570-FE.C.

FIGS. 41A-41I: Nucleotide (SEQ ID NO: 39) and deduced amino acid (SEQ IDNO: 40) sequence of Human IL-1 Trap 823.

FIGS. 42A-42I: Nucleotide (SEQ ID NO: 41) and deduced amino acid (SEQ IDNO: 42) sequence of Human IL-1 Trap 823-1198.B.

FIGS. 43A-43I: Nucleotide (SEQ ID NO: 43) and deduced amino acid (SEQ IDNO: 44) sequence of Human IL-1 Trap 823-1267.C.

FIGS. 44A-44I: Nucleotide (SEQ ID NO: 45) and deduced amino acid (SEQ IDNO: 46) sequence of Human IL-1 Trap 1647-CtF.

FIGS. 45A-45I: Nucleotide (SEQ ID NO: 47) and deduced amino acid (SEQ IDNO: 48) sequence of Human IL-1 Trap 1647-CtF.B.

FIGS. 46A-46I: Nucleotide (SEQ ID NO: 49) and deduced amino acid (SEQ IDNO: 50) sequence of Human IL-1 Trap 1647-CtF.C.

FIGS. 47A-47I: Nucleotide (SEQ ID NO: 51) and deduced amino acid (SEQ IDNO: 52) sequence of Human IL-1 Trap 1649.

FIGS. 48A-48I: Nucleotide (SEQ ID NO: 53) and deduced amino acid (SEQ IDNO: 54) sequence of Human IL-1 Trap 1649-B.

FIGS. 49A-49I: Nucleotide (SEQ ID NO: 55) and deduced amino acid (SEQ IDNO: 56) sequence of Human IL-1 Trap 1646-C.

FIG. 50: Human IL-1 Trap blocks the in vivo effects of exogenouslyadministered human IL-1. Male C57BL/6 mice were given a subcutaneousinjection of recombinant human IL-1β (rhIL-1β; 0.3 mg/kg). Twenty fourhours prior to rhIL-1β administration, animals were treated with eithervehicle, human IL-1 Trap 569 (50 or 150-fold molar excess; 0.18 or 0.54mg/kg, respectively), or recombinant murine IL-1 receptor antagonist(rmIL-1ra; 150 or 750-fold molar excess; 45.8 or 229 μg/kg,respectively). Blood samples were taken 2 h after administration ofrhIL-1β and the sera were assayed for IL-6 levels using a mouse IL-6ELISA. Exogenous administration of rhIL-1β significantly increased serumIL-6 levels. Pretreatment with either a 50 or 150-fold molar excess ofhIL-1 Trap blocked the rhIL-1β-induction of IL-6. In contrast, injectionof rmIL-1ra at either a 150 or 750-fold molar excess did not block IL-6induction.

FIG. 51: Human IL-1 Trap blocks the effects of IL-1 in Inflamed Joints.Anesthetized male C57BL/6 mice were given an intra-articular (i.a.)injection of Zymosan A (300 μg in 10 μl) into the right knee jointthrough the patellar ligament. Sterile PBS was injected i.a. (10 μl)into the left knee joint through the patellar ligament. Twenty fourhours prior to i.a. injections, animals were treated with either vehicleor hIL-1 Trap 569 (19 mg/kg, s.c.). The patellae were removed 24 h afterinjection of zymosan in order to measure proteoglycan synthesis, eachpatella and associated ligament were incubated for 3 h at 37° C., 5% CO₂in media (RPMI with HEPES, HCO₃, glutamine & penicillin/streptomycin)containing 10 uCi/ml ³⁵S-sulfate. Following incubation, tissue waswashed and fixed overnight in 10% formalin. The tissue was then placedin Decalcifing Solution for 4 h prior to dissection of the patella fromsurrounding tissue. Each patella was then incubated overnight inSolvable at 50° C. Ultima Gold liquid scintillation fluid was added andthe samples were counted in a liquid scintillation counter. Values werereported as the ratio of cpm of zymosan patella/cpm of vehicle patellafor each animal. Intra-articular injection of zymosan reducesproteoglycan synthesis by approximately 50% relative to vehicleinjection. Administration of hIL-1 Trap prior to zymosan injectionblocked the local action of IL-1β and proteoglycan synthesis returned toapproximately 90% of control.

FIGS. 52-53: Murine IL-1 Trap Reduces the Severity of Arthritis Symptomsin a Zymosan-Accelerated Collagen-Induced Arthritis (CIA) model. MaleDBA-1 mice were immunized intradermally at the base of the tail with 100μg/50 μl bovine Type II collagen (CII) emulsified with complete andincomplete Freund's adjuvant (2:1:1 ratio) and boosted intradermallywith CII (100 μg/50 μl) emulsified with incomplete Freund's adjuvant onday 21. Since CIA in DBA-1 mice occurs gradually over a long time periodwith a low incidence, we synchronized the onset of arthritis symptoms byinjecting the animals intraperitoneally on day 30 with 3 mg zymosan. Twohours prior to zymosan injection, the mice were randomly distributedinto treatment groups and were injected with either vehicle or mIL-1Trap (31 or 10 mg/kg, 3×/week, 8 injections, s.c.). Arthritis symptoms(ASI scores) in the paws were evaluated 3×/week by individuals who wereblinded to the treatment group. Animals were sacrificed 24 h after the8th injection at which time paw width along with ASI scores weremeasured. Within 5 days after i.p injection of zymosan, vehicle treatedanimals had an significant increase in ASI score relative to thosereceiving mIL-1 Trap with symptoms reaching a maximum 10 to 14 daysafter zymosan injection. Murine IL-1 Trap acted in a dose-dependentfashion such that animals receiving 10 mg/kg Trap had more arthritissymptoms (greater ASI score) than those receiving 31 mg/kg. However,both mIL-1 Trap treated groups had a significantly lower degree ofarthritis symptoms than vehicle. This difference in ASI score is alsoreflected in the paw width at the time of sacrifice (FIG. 67). Animalsreceiving mIL-1 Trap had paw widths that were similar to those of naive,non-collagen immunized animals

FIG. 54: Various concentrations of IL-1 Trap 1649 were incubated in thepresence of 5 pM human IL-1b overnight at room temperature. The mixtureswere then added to duplicate wells of 293-NFkB cells (20,000 cells/well)for 5 hrs at 37° C., 5% CO₂. Steady-Glo Reagent (Promega) was added tothe cells for 15 min at room temperature and luciferase gene expressionwas quantitated as relative light units (RLU) by luminometry. IL-1 Trap1649 displays an IC₅₀ of 32 pM.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an isolated nucleic acid moleculeencoding a fusion polypeptide capable of binding a cytokine to form anonfunctional complex comprising: (a) a nucleotide sequence encoding afirst fusion polypeptide component comprising the amino acid sequence ofthe cytokine binding portion of the extracellular domain of thespecificity determining component of a cytokine's receptor; (b) anucleotide sequence encoding a second fusion polypeptide componentcomprising the amino acid sequence of the cytokine binding portion ofthe extracellular domain of the signal transducing component of acytokine's receptor; and (c) a nucleotide sequence encoding a thirdfusion polypeptide component comprising the amino acid sequence of amultimerizing component.

By “cytokine binding portion” what is meant is the minimal portion ofthe extracellular domain necessary to bind the cytokine. It is acceptedby those of skill in the art that a defining characteristic of acytokine receptor is the presence of the two fibronectin-like domainsthat contain canonical cysteines and of the WSXWS box (Bazan 1990supra). Sequences encoding the extracellular domains of the bindingcomponent of the cytokine's receptor and of the signal transducingcomponent of the cytokine's receptor may also be used to create thefusion polypeptide of the invention. Similarly, longer sequencesencoding larger portions of the components of the cytokine's receptormay be used. However, it is contemplated that fragments smaller than theextracellular domain will function to bind the cytokine and therefore,the invention contemplates fusion polypeptides comprising the minimalportion of the extracellular domain necessary to bind the cytokine asthe cytokine binding portion.

The invention comprises a “specificity determining component” of acytokine receptor and a “signal transducing component” of the cytokinereceptor. Regardless of the nomenclature used to designate a particularcomponent or subunit of a cytokine receptor, one skilled in the artwould recognize which component or subunit of a receptor is responsiblefor determining the cellular target of the cytokine, and thus would knowwhich component constitutes the “specificity determining component.”

Similarly, regardless of the nomenclature used, one of skill in the artwould know which component or subunit of a receptor would constitute the“signal transducing component.” As used herein, the “signal transducingcomponent” is a component of the native receptor which is not thespecificity determining component and which does not bind or weaklybinds the cytokine in the absence of the specificity determiningcomponent. In the native receptor, the “signal transducing component”may participate in signaling.

For example, while some cytokine receptors have components designated αand β, the IL-4 receptor has a signal transducing component referred toas IL-2Rγ. However, regardless of what name is associated with thatcomponent, one skilled in the art would know which component of the IL-4receptor is the signal transducing component. Thus to practice thepresent invention and create a high affinity Trap for IL-4, one of skillin the art would create an isolated nucleic acid comprising a nucleotidesequence encoding a first fusion polypeptide component comprising theamino acid sequence of the cytokine binding portion of the extracellulardomain of the specificity determining component of the IL-4 receptor(IL-4Rα); a nucleotide sequence encoding a second fusion polypeptidecomponent comprising the amino acid sequence of the cytokine bindingportion of the extracellular domain of the signal transducing componentof the IL-4 receptor (IL-2Rγ); and a nucleotide sequence encoding athird fusion polypeptide component comprising the amino acid sequence ofa multimerizing component (for example, an Fc domain of IgG) to create ahigh affinity Trap for IL-4.

In preparing the nucleic acid sequence encoding the fusion polypeptideof the invention, the first, second, and third components of the fusionpolypeptide are encoded in a single strand of nucleotides which, whenexpressed by a host vector system, produces a monomeric species of thefusion polypeptide. The monomers thus expressed then multimerize due tothe interactions between the multimerizing components (the third fusionpolypeptide components). Producing the fusion polypeptides in thismanner avoids the need for purification of heterodimeric mixtures thatwould result if the first and second components were produced asseparate molecules and then multimerized. For example, U.S. Pat. No.5,470,952 describes the production of heterodimeric proteins thatfunction as CNTF or IL-6 antagonists. The heterodimers are purified fromcell lines co-transfected with the appropriate alpha (α) and beta (β)components. Heterodimers are then separated from homodimers usingmethods such as passive elution from preparative, nondenaturingpolyacrylamide gels or by using high pressure cation exchangechromatography. The need for this purification step is avoided by themethods of the present invention.

In addition, WO 96/11213 states that the applicant has preparedhomodimers in which two IL-4 receptors are bound by a polymeric spacerand has prepared heterodimers in which an IL-4 receptor is linked by apolymeric spacer to an IL-2 receptor gamma chain. The polymeric spacerdescribed is polyethylene glycol (PEG). The two receptor components,IL-4R and IL-2Rγ are separately expressed and purified. Pegylatedhomodimers and heterodimers are then produced by joining the componentstogether using bi-functional PEG reagents. It is an advantage of thepresent invention that it avoids the need for such time consuming andcostly purification and pegylation steps.

In one embodiment of the invention, the nucleotide sequence encoding thefirst component is upstream of the nucleotide sequence encoding thesecond component. In another embodiment of the invention, the nucleotidesequence encoding the first component is downstream of the nucleotidesequence encoding the second component. Further embodiments of theinvention may be prepared in which the order of the first, second andthird fusion polypeptide components are rearranged. For example, if thenucleotide sequence encoding the first component is designated 1, thenucleotide sequence encoding the second component is designated 2, andthe nucleotide sequence of the third component is designated 3, then theorder of the components in the isolated nucleic acid of the invention asread from 5′ to 3′ may be any of the following six combinations: 1,2,3;1,3,2; 2,1,3; 2,3,1; 3,1,2; or 3,2,1.

In further embodiments of the invention, the cytokine bound by thefusion polypeptide may be a member of the hematopoietin family ofcytokines selected from the group consisting of interleukin-2,interleukin-3, interleukin-4, interleukin-5, interleukin-6,interleukin-7, interleukin-9, interleukin-11, interleukin-13,interleukin-15, granulocyte macrophage colony stimulating factor,oncostatin M, leukemia inhibitory factor, and cardiotrophin-1.

In additional embodiments of the invention, the cytokine bound by thefusion polypeptide may be a member of the interferon family of cytokinesselected from the group consisting of IFN-γ, IFN-α, and IFN-β.

In additional embodiments of the invention, the cytokine bound by thefusion polypeptide may be a member of the immunoglobulin superfamily ofcytokines selected from the group consisting of B7.1 (CD80) and B7.2(B70).

In still further embodiments of the invention, the cytokine bound by thefusion polypeptide may be a member of the TNF family of cytokinesselected from the group consisting of TNF-α, TNF-βbeta, LT-β, CD40ligand, Fas ligand, CD 27 ligand, CD 30 ligand, and 4-1BBL.

In additional embodiments of the invention, the cytokine bound by thefusion polypeptide may be a cytokine selected from the group consistingof interleukin-1 (IL-1), IL-10, IL-12, IL-14, IL-18, and MIF.

Because specificity determination and signal transduction occurs by asimilar mechanism in the TGF-β/BMP family of cytokines (see, forexample, Kingsley 1994 Genes & Development 8:133-146) the presentinvention may be used to produce high affinity antagonists for cytokinesthat are members of the TGF-β/BMP family.

Therefore, in additional embodiments of the invention, the cytokinebound by the fusion polypeptide may be a member of the TGF-β/BMP familyselected from the group consisting of TGF-β1, TGF-β2, TGF-β3, BMP-2,BMP-3a, BMP-3b, BMP-4, BMP-5, BMP-6, BMP-7, BMP-8a, BMP-8b, BMP-9,BMP-10, BMP-11, BMP-15, BMP-16, endometrial bleeding associated factor(EBAF), growth differentiation factor-1 (GDF-1), GDF-2, GDF-3, GDF-5,GDF-6, GDF-7, GDF-8, GDF-9, GDF-12, GDF-14, mullerian inhibitingsubstance (MIS), activin-1, activin-2, activin-3, activin-4, andactivin-5.

In alternative embodiments of the invention, the specificity determiningcomponent, the signal transducing component, or both, may be substitutedfor by a single chain Fv. A single chain Fv (scFv) is a truncated Fabhaving only the V region of a heavy chain linked by a stretch ofsynthetic peptide to a V region of a light chain. (See, for example,U.S. Pat. Nos. 5,565,332; 5,733,743; 5,837,242; 5,858,657; and 5,871,907incorporated by reference herein). Thus the present inventioncontemplates, for example, an isolated nucleic acid molecule encoding afusion polypeptide capable of binding a cytokine to form a nonfunctionalcomplex comprising a nucleotide sequence encoding a first fusionpolypeptide component comprising the amino acid sequence of the cytokinebinding portion of the extracellular domain of the specificitydetermining component of the cytokine receptor; a nucleotide sequenceencoding a second fusion polypeptide component comprising the amino acidsequence of an scFv capable of binding the cytokine at a site differentfrom the site at which the cytokine binding portion of the extracellulardomain of the specificity determining component of the cytokine receptorbinds; and a nucleotide sequence encoding a third fusion polypeptidecomponent comprising the amino acid sequence of a multimerizingcomponent. Alternatively, the specificity determining component may besubstituted for by a scFv that binds to a site on the cytokine differentfrom the site at which the signal transducing component binds. Thus theinvention contemplates an isolated nucleic acid molecule encoding afusion polypeptide capable of binding a cytokine to form a nonfunctionalcomplex comprising a nucleotide sequence encoding a first fusionpolypeptide component comprising the amino acid sequence of a scFv thatbinds to a site on the cytokine different from the site at which thecytokine binding portion of the extracellular domain of the signaltransducing component of the cytokine receptor binds; a nucleotidesequence encoding a second fusion polypeptide component comprising theamino acid sequence of the cytokine binding portion of the extracellulardomain of the signal transducing component of the cytokine's receptor;and a nucleotide sequence encoding a third fusion polypeptide componentcomprising the amino acid sequence of a multimerizing component.

In another embodiment, the invention contemplates an isolated nucleicacid molecule encoding a fusion polypeptide capable of binding acytokine to form a nonfunctional complex comprising a nucleotidesequence encoding a first fusion polypeptide component comprising theamino acid sequence of a first scFv that binds to a site on thecytokine; a nucleotide sequence encoding a second fusion polypeptidecomponent comprising the amino acid sequence a second scFv that binds toa site on the cytokine different from the site at which the first scFvbinds; and a nucleotide sequence encoding a third fusion polypeptidecomponent comprising the amino acid sequence of a multimerizingcomponent.

In all of the above described embodiments comprising scFvs, theinvention also contemplates embodiments in which the nucleotide sequenceencoding the first component is upstream of the nucleotide sequenceencoding the second component; embodiments in which the nucleotidesequence encoding the first component is downstream of the nucleotidesequence encoding the second component; and further embodiments of theinvention in which the order of the first, second and third fusionpolypeptide components is rearranged. For example, if the nucleotidesequence encoding the first component is designated 1, the nucleotidesequence encoding the second component is designated 2, and thenucleotide sequence of the third component is designated 3, then theorder of the components in the isolated nucleic acid of the invention asread from 5′ to 3′ may be any of the following six combinations: 1,2,3;1,3,2; 2,1,3; 2,3,1; 3,1,2; or 3,2,1.

In preferred embodiments of the invention, the multimerizing componentcomprises an immunoglobulin derived domain. More specifically, theimmunoglobulin derived domain may be selected from the group consistingof the Fc domain or the heavy chain of IgG. Even more specifically,immunoglobulin domain may be selected from the group consisting of theFc domain or the heavy chain of IgG₁ or IgG₄. In another embodiment, themultimerizing component may be an Fc domain from which the first fiveamino acids (including a cysteine) have been removed to produce amultimerizing component referred to as Fc(DCI). Alternatively, themultimerizing component may be an Fc domain in which a cysteine withinthe first five amino acids has been substituted for by another aminoacid such as, for example, serine or alanine.

The present invention also provides for fusion polypeptides encoded bythe isolated nucleic acid molecules of the invention. Preferably, thefusion polypeptides are in multimeric form, due to the function of thethird component, the multimerizing component. In a preferred embodiment,the multimer is a dimer. Suitable multimerizing components are sequencesencoding an immunoglobulin heavy chain hinge region (Takahashi et al.1982 supra); immunoglobulin gene sequences, and portions thereof. In apreferred embodiment of the invention, immunoglobulin gene sequences,especially one encoding the Fc domain, are used to encode themultimerizing component.

The present invention also contemplates a vector which comprises thenucleic acid molecule of the invention as described herein.

A preferred embodiment of the invention is an isolated nucleic acidmolecule having the sequence set forth in SEQ ID NO:33 encoding a fusionpolypeptide having the sequence set forth in SEQ ID NO:34, wherein thefusion polypeptide forms a multimer that is capable of binding acytokine to form a nonfunctional complex; an isolated nucleic acidmolecule having the sequence set forth in SEQ ID NO:35 encoding a fusionpolypeptide having the sequence set forth in SEQ ID NO:36, wherein thefusion polypeptide forms a multimer that is capable of binding acytokine to form a nonfunctional complex; and an isolated nucleic acidmolecule having the sequence set forth in SEQ ID NO:37 encoding a fusionpolypeptide having the sequence set forth in SEQ ID NO:38, wherein thefusion polypeptide forms a multimer that is capable of binding acytokine to form a nonfunctional complex; as well as fusion polypeptidesencoded by the above-described nucleic acid molecules.

Other preferred embodiments of the invention are isolated nucleic acidmolecules having the sequences set forth in SEQ ID NO: 39, 41, 43, 45,47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81,or 83 encoding fusion polypeptides having the sequences set forth in SEQID NO: 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70,72, 74, 76, 78, 80, 82, or 84, respectively, wherein each fusionpolypeptide forms a multimer that is capable of binding IL-1 to form anon-functional complex.

Also provided is an expression vector comprising a nucleic acid moleculeof the invention as described herein, wherein the nucleic acid moleculeis operatively linked to an expression control sequence. Also providedis a host-vector system for the production of a fusion polypeptidecomprising the expression vector of the invention which has beenintroduced into a host cell suitable for expression of the fusionpolypeptide. The suitable host cell may be a bacterial cell such as E.coli, a yeast cell, such as Pichia pastoris, an insect cell, such asSpodoptera frugiperda, or a mammalian cell, such as a COS, CHO, 293, BHKor NS0 cell.

The present invention also provides for methods of producing the fusionpolypeptides of the invention by growing cells of the host-vectorsystems described herein, under conditions permitting production of thefusion polypeptide and recovering the fusion polypeptide so produced.

The present invention provides novel antagonists which are based onreceptor components that are shared by cytokines such as the CNTF familyof cytokines.

The invention described herein contemplates the production ofantagonists to any cytokine that utilizes an a specificity determiningcomponent which, when combined with the cytokine, binds to a first βsignal transducing component to form a nonfunctional intermediate whichthen binds to a second β signal transducing component causing β-receptordimerization and consequent signal transduction. According to theinvention, the soluble α specificity determining component of thereceptor (sRα) and the extracellular domain of the first β signaltransducing component of the cytokine receptor (β1) are combined to formheterodimers (sRα:β1) that act as antagonists to the cytokine by bindingthe cytokine to form a nonfunctional complex.

The invention described herein also contemplates the production ofantagonists to any cytokine that utilizes an a specificity determiningcomponent which, when combined with the cytokine, binds to a β signaltransducing component to form a receptor complex which then initiatessignal transduction. According to the invention, the soluble aspecificity determining component of the receptor (sRα) and theextracellular domain of the β signal transducing component of thecytokine receptor (b) are combined to form heterodimers (sRα:β) that actas antagonists to the cytokine by binding the cytokine to form anonfunctional complex.

As described in Example 1, CNTF and IL-6 share the β1 receptor componentgp130. The fact that CNTF forms an intermediate with CNTFRα and gp130can be demonstrated (Example 1) in cells lacking LIFRβ, where thecomplex of CNTF and CNTFRα binds gp130, and prevents homodimerization ofgp130 by IL-6 and IL-6Rα, thereby blocking signal transduction. Thesestudies provide the basis for the development of the IL-6 antagonistsdescribed herein, as they show that if, in the presence of a ligand, anonfunctional intermediate complex, consisting of the ligand, its areceptor component and its b1 receptor component, can be formed, it willeffectively block the action of the ligand. Other cytokines may useother β1 receptor components, such as LIFRβ, which may also be used toproduce antagonists according to the present invention.

Thus for example, in one embodiment of the invention, effectiveantagonists of IL-6 or CNTF consist of heterodimers of the extracellulardomains of the a specificity determining components of their receptors(sIL-6Rα and sCNTFRα, respectively) and the extracellular domain ofgp130. The resultant heterodimers, which are referred to hereinafter assIL-6Rα:β1 and sCNTFRα:β1, respectively, function as high-affinity Trapsfor IL-6 or CNTF, respectively, thus rendering the cytokine inaccessibleto form a signal transducing complex with the native membrane-boundforms of their receptors.

Although soluble ligand binding domains from the extracellular portionof receptors have proven to be somewhat effective as Traps for theirligands and thus act as antagonists (Bargetzi et al. 1993 Cancer Res53:4010-4013; and 1992 Proc. Natl. Acad. Sci. USA 89:8616-8620; Mohleret al. 1993 J. Immunol. 151: 1548-1561; Narazaki et al. 1993 Blood82:1120-1126), the IL-6 and CNTF receptors are unusual in that the αreceptor components constitute ligand binding domains that, in concertwith their ligands, function effectively in soluble form as receptoragonists (Davis et al. 1993 supra; Taga et al. 1989 Cell 58: 573-581).The sRα:β1 heterodimers prepared according to the present inventionprovide effective Traps for their ligands, binding these ligands withaffinities in the picomolar range (based on binding studies for CNTF toPC12D cells) without creating functional intermediates. The technologydescribed herein may be applied to develop a cytokine Trap for anycytokine that utilizes an α-component that confers specificity, as wellas a β component which, when bound to the α-specificity component, has ahigher affinity for the cytokine than either component alone.Accordingly, antagonists according to the invention include antagonistsof IL-1 through IL-5 (IL-1: Greenfeder, et al. 1995 J Biol Chem270:13757-13765; Guo et al. 1995 J Biol Chem 270:27562-27568), IL-2(Taniguchi et al. EP 0386289-A and 0386304-A; Takeshita et al. 1992Science 257:379-382); IL-3 (Kitamura et al. 1991 Cell 66:1165-1174),IL-4 (Idzerda et al. 1990 J Exp Med 171:861-873), IL-5 (Taverneir et al.1991 Cell 66:1175-1184), IL-11 (Cherel et al. EMBL/GenBank/DDBJdatabases Accession No. Z38102), IL-15 (Hemar et al. 1995 J Cell Biol1295:55-64); Taniguchi et al. EP 0386289-A and 0386304-A); Takeshita etal. 1992 Science 257:379-382), granulocyte-macrophage colony stimulatingfactor (GM-CSF) Hayashida et al. 1990 Proc. Natl. Acad. Sci. U.S.A.97:9655-9659), LIF, γ-interferon (Aguet 1988 et al. Cell 55:273-280; Sohet al. 1994 Cell 76:793-802), and transforming growth factor beta (TGFβ)(Inagaki et al. 1993 Proc. Natl. Acad. Sci. USA 90:5359-5363).

The α and β receptor extracellular domains may be prepared using methodsknown to those skilled in the art. The CNTFRa receptor has been cloned,sequenced and expressed (Davis et al. 1991 Science 253:59-63 which isincorporated by reference in its entirety herein). The cloning of LIFRβand gp130 are described in Gearing et al. 1991 EMBO J. 10:2839-2848,Hibi et al. 1990 supra and WO 93/10151, all of which are incorporated byreference in their entirety herein.

The receptor molecules useful for practicing the present invention maybe prepared by cloning and expression in a prokaryotic or eukaryoticexpression system. The recombinant receptor gene may be expressed andpurified utilizing any number of methods. The gene encoding the factormay be subcloned into a bacterial expression vector, such as forexample, but not by way of limitation, pCP110.

The recombinant factors may be purified by any technique which allowsfor the subsequent formation of a stable, biologically active protein.For example, and not by way of limitation, the factors may be recoveredfrom cells either as soluble proteins or as inclusion bodies, from whichthey may be extracted quantitatively by 8M guanidinium hydrochloride anddialysis. In order to further purify the factors, conventional ionexchange chromatography, hydrophobic interaction chromatography, reversephase chromatography or gel filtration may be used.

The sRα:β heterodimeric receptors may be engineered using known fusionregions, as described in WO 93/10151 which describes production of βreceptor heterodimers, or they may be prepared by crosslinking ofextracellular domains by chemical means. The domains utilized mayconsist of the entire extracellular domain of the a and b components, orthey may consist of mutants or fragments thereof that maintain theability to form a complex with its ligand and other components in thesRα:β1 complex. For example, as described below in Example 4, IL-6antagonists have been prepared using gp130 that is lacking its threefibronectin-like domains.

In one embodiment of the invention, the extracellular domains areengineered using leucine zippers. The leucine zipper domains of thehuman transcription factors c-jun and c-fos have been shown to formstable heterodimers (Busch et al. 1990 Trends Genetics 6:36-40; Gentz etal. 1989 Science 243:1695-1699) with a 1:1 stoichiometry. Althoughjun-jun homodimers have also been shown to form, they are about1000-fold less stable than jun-fos heterodimers. Fos-fos homodimers havenot been detected.

The leucine zipper domain of either c-jun or c-fos are fused in frame atthe C-terminus of the soluble or extracellular domains of the abovementioned receptor components by genetically engineering chimeric genes.The fusions may be direct or they may employ a flexible linker domain,such as the hinge region of human IgG, or polypeptide linkers consistingof small amino acids such as glycine, serine, threonine or alanine, atvarious lengths and combinations. Additionally, the chimeric proteinsmay be tagged by His-His-His-His-His-His (His6) (SEQ. ID NO. 1) to allowrapid purification by metal-chelate chromatography, and/or by epitopesto which antibodies are available, to allow for detection on westernblots, immunoprecipitation, or activity depletion/blocking in bioassays.

In another embodiment, as described below in Example 3, the sRα:β1heterodimer is prepared using a similar method, but using the Fc-domainof human IgG1 (Aruffo et al. 1991 Cell 67:35-44). In contrast to thelatter, formation of heterodimers must be biochemically achieved, aschimeric molecules carrying the Fc-domain will be expressed asdisulfide-linked homodimers. Thus, homodimers may be reduced underconditions that favor the disruption of inter-chain disulfides but donot effect intra-chain disulfides. Then monomers with differentextracellular portions are mixed in equimolar amounts and oxidized toform a mixture of homo- and heterodimers. The components of this mixtureare separated by chromatographic techniques. Alternatively, theformation of this type of heterodimers may be biased by geneticallyengineering and expressing molecules that consist of the soluble orextracellular portion of the receptor components followed by theFc-domain of hIgG, followed by either the c-jun or the c-fos leucinezippers described above (Kostelny et al. 1992 J Immunol 148:1547-1553).Since these leucine zippers form predominately heterodimers, they may beused to drive formation of the heterodimers where desired. As for thechimeric proteins described using leucine zippers, these may also betagged with metal chelates or an epitope. This tagged domain can be usedfor rapid purification by metal-chelate chromatography, and/or byantibodies, to allow for detection on western blots,immunoprecipitation, or activity depletion/blocking in bioassays.

In additional embodiments, heterodimers may be prepared using otherimmunoglobulin derived domains that drive the formation of dimers. Suchdomains include, for example, the heavy chains of IgG (Cg1 and Cg4), aswell as the constant regions of kappa (κ) and lambda (λ) light chains ofhuman immunoglobulins. The heterodimerization of Cγ with the light chainoccurs between the CH1 domain of Cγ and the constant region of the lightchain (C_(L)), and is stabilized by covalent linking of the two domainsvia a single disulfide bridge. Accordingly, as described in Example 4,constructs may be prepared using these immunoglobulin domains.Alternatively, the immunoglobulin domains include domains that may bederived from T cell receptor components which drive dimerization.

In another embodiment of the invention, the sRα:β1 heterodimers areprepared by expression as chimeric molecules utilizing flexible linkerloops. A DNA construct encoding the chimeric protein is designed suchthat it expresses two soluble or extracellular domains fused together intandem (“head to head”) by a flexible loop. This loop may be entirelyartificial (e.g. polyglycine repeats interrupted by serine or threonineat a certain interval) or “borrowed” from naturally occurring proteins(e.g. the hinge region of hIgG). Molecules may be engineered in whichthe order of the soluble or extracellular domains fused is switched(e.g. sIL6Rα/loop/sgp130 or sgp130/loop/sIL-6Rα) and/or in which thelength and composition of the loop is varied, to allow for selection ofmolecules with desired characteristics.

Alternatively, the heterodimers made according to the present inventionmay be purified from cell lines cotransfected with the appropriate α andβ components. Heterodimers may be separated from homodimers usingmethods available to those skilled in the art. For example, limitedquantities of heterodimers may be recovered by passive elution frompreparative, nondenaturing polyacrylamide gels. Alternatively,heterodimers may be purified using high pressure cation exchangechromatography. Excellent purification has been obtained using a Mono Scation exchange column.

In addition to sRα:β1 heterodimers that act as antagonists by bindingfree CNTF or IL-6, the present invention also contemplates the use ofengineered, mutated versions of IL-6 with novel properties that allow itto bind to IL-6Rα and a single gp130 molecule, but fail to engage thesecond gp130 to complete β component homodimerization, and thus act asan effective IL-6 antagonist on any IL-6 responsive cell. Our model forthe structure of the IL-6 and CNTF receptor complexes indicates thatthese cytokines have distinct sites for binding the α, β1, and β2receptor components (Stahl et al. 1993 supra). Mutations of criticalamino acid residues comprising each of these sites gives rise to novelmolecules which have the desired antagonistic properties. Ablation ofthe b1 site would give a molecule which could still bind to the areceptor component but not the β1 component, and thereby comprise anantagonist with nanomolar affinity. Mutations of critical amino acidresidues comprising the β2 site of IL-6 (IL-6β2⁻) would give a moleculethat would bind to IL-6Rα and the first gp130 monomer, but fail toengage the second gp130 and thus be functionally inactive. Similarly,mutations of the CNTF β2 site would give a molecule (CNTFβ2⁻) that wouldbind CNTFRα and gp130, but fail to engage LIFRβ, thereby antagonizingCNTF action by forming the non-functional β1 intermediate. Based on thebinding results described above where CNTF forms the β1 intermediatewith high affinity, both CNTFβ2⁻ and IL-β2⁻ would constitute antagonistswith affinity in the range of 10 pM.

A variety of means are used to generate and identify mutations of IL-6or CNTF that have the desired properties. Random mutagenesis by standardmethods of the DNA encoding IL-6 or CNTF may be used, followed byanalysis of the collection of products to identify mutated cytokineshaving the desired novel properties as outlined below. Mutagenesis bygenetic engineering has been used extensively in order to elucidate thestructural organization of functional domains of recombinant proteins.Several different approaches have been described in the literature forcarrying out deletion or substitution mutagenesis. The most successfulappear to be alanine scanning mutagenesis (Cunningham et al. 1989Science 244:1081-1085) and homolog-scanning mutagenesis (Cunningham etal. 1989 Science 243:1330-1336).

Targeted mutagenesis of the IL-6 or CNTF nucleic acid sequences usingsuch methods can be used to generate CNTFβ2- or IL-6β2-candidates. Thechoice of regions appropriate for targeted mutagenesis is donesystematically, or determined from studies whereby panels of monoclonalantibodies against each factor are used to map regions of the cytokinethat might be exposed after binding of the cytokine to the a receptorcomponent alone, or to the ab1 heterodimeric soluble receptors describedabove. Similarly, chemical modification or limited proteolysis of thecytokine alone or in a complex bound to the a receptor component or theab1 heterodimeric soluble receptors described above, followed byanalysis of the protected and exposed regions could reveal potential β2binding sites.

Assays for identifying CNTF or IL-6 mutants with the desired propertiesinvolve the ability to block with high affinity the action of IL-6 orCNTF on appropriately responsive cell lines (Davis et al. 1993 supra;Murakami et al. 1991 Proc Natl Acad Sci USA 88:11349-11353). Such assaysinclude cell proliferation, survival, or DNA synthesis driven by CNTF orIL-6, or the construction of cell lines where binding of factor inducesproduction of reporters such as CAT or β-galactosidase (Savino et al.1993 Proc Natl Acad Sci USA 90:4067-4071).

Alternatively, the properties of various mutants may be assessed with areceptor-based assay. One such assay consists of screening mutants fortheir ability to bind the sRα:β1 receptor heterodimers described aboveusing epitope-tagged (Davis et al. 1991 supra) sRα:β1 reagents.Furthermore, one can probe for the presence or absence of the β2 site byassessing whether an epitope-tagged soluble β2 reagent will bind to thecytokine in the presence of the β1 heterodimer. For example, CNTF onlybinds to LIFRβ (the β2 component) in the presence of both CNTFRα andgp130 (Davis et al. 1993 supra; Stahl et al. 1993 supra). Thus a solubleLIFRβ reagent would only bind to CNTF in the presence of the solublesRα:β1 dimer sCNTFRα:β1. For IL-6, the sRα:β1 reagent would beIL-6Rα:β1, and the probe for the β2 site would be epitope-tagged sgp130.Thus β2-mutants of CNTF would be identified as those that bound thesRα:β1 reagent, demonstrating that the α and β1 site of the cytokinewere intact, yet failed to bind the β2 reagent.

In addition, the present invention provides for methods of detecting ormeasuring the activity of potential β2⁻ mutants by measuring thephosphorylation of a β-receptor component or a signal transductioncomponent selected from the group consisting of Jak1, Jak2 and Tyk2 orany other signal transduction component, such as the CLIPs, that aredetermined to be phosphorylated in response to a member of the CNTFfamily of cytokines.

A cell that expresses the signal transduction component(s) describedherein may either do so naturally or be genetically engineered to do so.For example, Jak1 and Tyk-2-encoding nucleic acid sequences obtained asdescribed in Velazquez et al. 1992 Cell 70:313-322, may be introducedinto a cell by transduction, transfection, microinjection,electroporation, via a transgenic animal, etc., using any known methodknown in the art.

According to the invention, cells are exposed to a potential antagonistand the tyrosine phosphorylation of either the β-component(s) or thesignal transduction component(s) are compared to the tyrosinephosphorylation of the same component(s) in the absence of the potentialantagonist.

In another embodiment of the invention, the tyrosine phosphorylationthat results from contacting the above cells with the potentialantagonist is compared to the tyrosine phosphorylation of the same cellsexposed to the parental CNTF family member. In such assays, the cellmust either express the extracellular receptor (α-component) or thecells may be exposed to the test agent in the presence of the solublereceptor component. Thus, for example, in an assay system designed toidentify agonists or antagonists of CNTF, the cell may express theα-component CNTFRα, the β-components gp130 and LIFRβ and a signaltransducing component such as Jak1. The cell is exposed to test agents,and the tyrosine phosphorylation of either the β-components or thesignal transducing component is compared to the phosphorylation patternproduced in the presence of CNTF. Alternatively, the tyrosinephosphorylation which results from exposure to a test agent is comparedto the phosphorylation which occurs in the absence of the test agent.Alternatively, an assay system, for example, for IL-6 may involveexposing a cell that expresses the β-component gp130 and a signaltransducing protein such as Jak1, Jak2 or Tyk2 to a test agent inconjunction with the soluble IL-6 receptor.

In another embodiment of the invention the above approaches are used todevelop a method for screening for small molecule antagonists that actat various steps in the process of ligand binding, receptor complexformation, and subsequent signal transduction. Molecules thatpotentially interfere with ligand-receptor interactions are screened byassessing interference of complex formation between the solublereceptors and ligand as described above. Alternatively, cell-basedassays in which IL-6 or CNTF induce response of a reporter gene arescreened against libraries of small molecules or natural products toidentify potential antagonists. Those molecules showing antagonistactivity are rescreened on cell-based assays responding to other factors(such as GM-CSF or factors like Neurotrophin-3 that activate receptortyrosine kinases) to evaluate their specificity against theCNTF/IL-6/OSM/LIF family of factors. Such cell-based screens are used toidentify antagonists that inhibit any of numerous targets in the signaltransduction process.

In one such assay system, the specific target for antagonists is theinteraction of the Jak/Tyk family of kinases (Firmbach-Kraft 1990Oncogene 5:1329-1336; Wilks et al. 1991 Mol Cell Biol 11:2057-2065) withthe receptor β subunits. As described above, LIFRβ and gp130preassociate with members of the Jak/Tyk family of cytoplasmic proteintyrosine kinases, which become activated in response to ligand-induced βcomponent dimerization (Stahl et al. 1993 supra). Thus small moleculesthat could enter the cell cytoplasm and disrupt the interaction betweenthe β component and the Jak/Tyk kinase could potentially block allsubsequent intracellular signaling. Such activity could be screened withan in vitro scheme that assessed the ability of small molecules to blockthe interaction between the relevant binding domains of purified βcomponent and Jak/Tyk kinase. Alternatively, one could easily screen formolecules that could inhibit a yeast-based assay of b component bindingto Jak/Tyk kinases using the two-hybrid interaction system (Chien et al.1991 Proc. Natl. Acad. Sci. 88: 9578-9582). In such a system, theinteraction between two proteins (β component and Jak/Tyk kinase orrelevant domains thereof in this example) induces production of aconvenient marker such as β-galactosidase. Collections of smallmolecules are tested for their ability to disrupt the desiredinteraction without inhibiting the interaction between two controlproteins. The advantage of this screen would be the requirement that thetest compounds enter the cell before inhibiting the interaction betweenthe b component and the Jak/Tyk kinase.

The CNTF family antagonists described herein either bind to, or competewith the cytokines CNTF and IL-6. Accordingly, they are useful fortreating diseases or disorders mediated by CNTF or IL-6. For example,therapeutic uses of IL-6 antagonists would include the following: (1) Inosteoporosis, which can be exacerbated by lowering of estrogen levels inpost-menopausal women or through ovariectomy, IL-6 appears to be acritical mediator of osteoclastogenesis, leading to bone resorption(Horowitz 1993 Science 260:626-627; Jilka et al. 1992 Science257:88-91). Importantly, IL-6 only appears to play a major role in theestrogen-depleted state, and apparently is minimally involved in normalbone maintenance. Consistent with this, experimental evidence indicatesthat function-blocking antibodies to IL-6 can reduce the number ofosteoclasts (Jilka et al. 1992 Science 257:88-91). While estrogenreplacement therapy is also used, there appear to be side effects thatmay include increased risk of endometrial and breast cancer. Thus, IL-6antagonists as described herein would be more specific to reduceosteoclastogenesis to normal levels; (2) IL-6 appears to be directlyinvolved in multiple myeloma by acting in either an autocrine orparacrine fashion to promote tumor formation (van Oers et al. 1993 AnnHematol 66:219-223). Furthermore, the elevated IL-6 levels createundesirable secondary effects such as bone resorption, hypercalcemia,and cachexia; in limited studies function-blocking antibodies to IL-6 orIL-6Rα have some efficacy (Klein et al. 1991 Blood 78:1198-1204; Suzukiet al. 1992 Eur J Immunol 22:1989-1993). Therefore, IL-6 antagonists asdescribed herein would be beneficial for both the secondary effects aswell as for inhibiting tumor growth; (3) IL-6 may be a mediator of tumornecrosis factor (TNF) that leads to cachexia associated with AIDS andcancer (Strassmann et al. 1992 J Clin Invest 89:1681-1684), perhaps byreducing lipoprotein lipase activity in adipose tissue (Greenberg et al.1992 Cancer Research 52:4113-4116). Accordingly, antagonists describedherein would be useful in alleviating or reducing cachexia in suchpatients.

Effective doses useful for treating these or other CNTF family relateddiseases or disorders may be determined using methods known to oneskilled in the art [see, for example, Fingl et al. 1975 ThePharmacological Basis of Therapeutics, Goodman and Gilman, eds.Macmillan Publishing Co., New York, pp. 1-46). Pharmaceuticalcompositions for use according to the invention include the antagonistsdescribed above in a pharmacologically acceptable liquid, solid orsemi-solid carrier, linked to a carrier or targeting molecule (e.g.,antibody, hormone, growth factor, etc.) and/or incorporated intoliposomes, microcapsules, and controlled release preparation (includingantagonist expressing cells) prior to administration in vivo. Forexample, the pharmaceutical composition may comprise one or more of theantagonists in an aqueous solution, such as sterile water, saline,phosphate buffer or dextrose solution. Alternatively, the active agentsmay be comprised in a solid (e.g. wax) or semi-solid (e.g. gelatinous)formulation that may be implanted into a patient in need of suchtreatment. The administration route may be any mode of administrationknown in the art, including but not limited to intravenously,intrathecally, subcutaneously, by injection into involved tissue,intraarterially, intranasally, orally, or via an implanted device.

Administration may result in the distribution of the active agent of theinvention throughout the body or in a localized area. For example, insome conditions which involve distant regions of the nervous system,intravenous or intrathecal administration of agent may be desirable. Insome situations, an implant containing active agent may be placed in ornear the lesioned area. Suitable implants include, but are not limitedto, gelfoam, wax, or microparticle-based implants.

EXAMPLES Example 1 CNTF Competes with IL-6 for Binding to gp130

Materials and methods. A clone of PC12 cells that respond to IL-6(PC12D) was obtained from DNAX. Rat CNTF was prepared as described(Masiakowski et al. 1991 J Neurochem 57:1003-10012). IL-6 and sIL-6Rawere purchased from R & D Systems. Antisera was raised in rabbitsagainst a peptide derived from a region near the C-terminus of gp130(CGTEGQVERFETVGME) (SEQ ID NO:2) by the method of Stahl et al. 1993 JBiol Chem 268:7628-7631. Anti-phosphotyrosine monoclonal 4G10 waspurchased from UBI, and reagents for ECL from Amersham.

Signal Transduction Assays. Plates (10 cm) of PC12D were starved inserum-free medium (RPMI 1640+glutamine) for 1 hour, then incubated withIL-6 (50 ng/mL)+sIL-6R (1 mg/mL) in the presence or absence of added ratCNTF at the indicated concentrations for 5 minutes at 37° C. Sampleswere then subjected to anti-gp130 immunoprecipitation, SDS PAGE, andanti-phosphotyrosine immunoblotting.

Results. The ability of CNTF to block IL-6 responses was measured usinga PC12 cell line (called PC12D) that expresses IL-6Rα, gp130, andCNTFRα, but not LIFRb. As one would predict, these cells respond toIL-6, but not to CNTF (FIG. 2) since LIFRβ is a required component forCNTF signal transduction (Davis et al. 1993 supra). In accordance withresults on other cell lines (Ip et al. 1992 supra), PC12D cells givetyrosine phosphorylation of gp130 (as well as a variety of otherproteins called CLIPs) in response to 2 nM IL-6 (FIG. 2). Addition ofrecombinant soluble IL-6Ra (sIL-6Ra) enhances the level of gp130tyrosine phosphorylation, as has been reported in some other systems(Taga et al. 1989 supra). However, addition of 2 nM CNTF simultaneouslywith IL-6 severely diminishes the tyrosine phosphorylation of gp130.Although a slight gp130 phosphorylation response remains in the presenceof CNTF, IL-6, and sIL-6Rα, it is eliminated if the CNTF concentrationis increased fourfold to 8 nM. Thus, in IL-6 responsive cells thatcontain CNTFRa but no LIFRb, CNTF is a rather potent antagonist of IL-6action.

Example 2 Binding of CNTF to the CNTFRα:β

Scatchard Analysis of CNTF Binding. ¹²⁵I-CNTF was prepared and purifiedas described [Stahl et al. 1993 supra). Saturation binding studies werecarried out in PC12 cells, using concentrations of ¹²⁵I-CNTF rangingfrom 20 pM to 10 nM. Binding was performed directly on a monolayer ofcells. Medium was removed from wells and cells were washed once withassay buffer consisting of phosphate buffered saline (PBS; pH 7.4), 0.1mM bacitracin, 1 mM PMSF, 1 mg/ml leupeptin, and 1 mg/ml BSA. Cells wereincubated in ¹²⁵I-CNTF for 2 hours at room temperature, followed by 2quick washes with assay buffer. Cells were lysed with PBS containing 1%SDS and counted in a Packard Gamma Counter at 90-95% efficiency.Non-specific binding was defined by the presence of 100-fold excess ofunlabelled CNTF. Specific binding ranged from 70% to 95%.

Results. The equilibrium constant for binding of CNTF to CNTFRα:β1 wasestimated from Scatchard analysis of iodinated CNTF binding on PC12Dcells (FIG. 3). The data is consistent with a 2 site fit havingdissociation constants of 9 pM and 3.4 nM. The low affinity sitecorresponds to interaction of CNTF with CNTFRα, which has a Kd near 3 nM(Panayotatos et al. 1993 J Biol Chem 268: 19000-19003). We interpret thehigh affinity complex as the intermediate containing CNTF, CNTFRa, andgp130. A Ewing sarcoma cell line (EW-1) which does contain CNTFRα,gp130, and LIFRβ, and therefore gives robust tyrosine phosphorylation inresponse to CNTF, displays a very similar two site fit with dissociationconstants of 1 nM and 10. Thus it is apparent that CNTF binds withequally high affinity to a complex containing only CNTFR and gp130, asit does to a complex which additionally contains LIFRβ, thusdemonstrating the feasibility of creating the sRα:β antagonistsdescribed herein.

Example 3 Methods of Producing Cytokine Ligand Traps

Virus Stock Production. SF21 insect cells obtained from Spodopterafrugiperda were grown at 27° C. in Gibco SF900 II medium to a density of1×10⁶ cells/mL. The individual virus stock for either GP130-Fc-His₆(FIGS. 4A-4B, SEQ ID NO:7) or IL6Rα-Fc (FIG. 5, SEQ ID NO:8) was addedto the bioreactor to a low multiplicity 0.01-0.1 PFU/cell to begin theinfection. The infection process was allowed to continue for 5-7 daysallowing maximum virus replication without incurring substantial celllysis. The cell suspension was aseptically aliquoted into sterilecentrifuge bottles and the cells removed by centrifugation. Thecell-free supernatant was collected in sterile bottles and stored at 4°C. until further use.

The virus titer was determined by plaque assay and is carried out in 60mm tissue-culture dishes which are seeded with 2×10⁶ cells. Serialdilutions of the virus stock are added to the attached cells and themixture incubated with rocking to allow the virus to adsorb toindividual cells. An agar overlay is added and plates incubated for 5-7days at 27° C. Staining of viable cells with neutral red revealedcircular plaques resulting which were counted to give the virus titer.

Coinfection of Cells for Protein Production. Uninfected SF21 Cells weregrown in a 60 L ABEC bioreactor containing 40 L of SF900 II medium.Temperature was controlled at 27° C. and the dissolved oxygen level wasmaintained at 50% of saturation by controlling the flow rate of oxygenin the inlet gas stream. When a density of 2×10⁶ cells/mL was reached,the cells were concentrated within the bioreactor to a volume of 20Lusing a low shear steam sterilizable pump with a tangential flowfiltration device with Millipore Prostak 0.65 micron membranes. Afterconcentration fresh sterile growth medium is slowly added to thebioreactor while the filtration system continues to remove the spentgrowth medium by diafiltration. After two volume exchanges (40L) havebeen carried out an additional 20L of fresh medium was added to thebioreactor to resuspend the cells to the original volume of 40L. Thecell density was determined once again by counting viable cells using ahemacytometer.

The required amount of each virus stock was calculated based on the celldensity, virus titer and the desired multiplicity of infection (MOI).Virus stock ratios of 5:1, 5:2, 10:2 and 10:4, IL6Ra-Fc to GP130-Fc-His₆all resulted in production of significant amounts of heterodimer. Theideal virus stock ratio is highly dependent on the ease of purificationof the heterodimer from each of the two homodimers. The IL6Rα-Fchomodimer is relatively easy to remove downstream by immobilized metalaffinity chromatography. Virus infection ratios have been chosen tominimize the formation of the GP130-Fc-His₆ homodimer which is moredifficult to clear downstream. The relative amount of GP130-Fc-His₆virus stock chosen for infection has increased with successive batchesas the purification method for clearing the resultant homodimer hasimproved.

The virus stocks were aseptically mixed in a single vessel thentransferred to the bioreactor. This results in synchronous infection ofthe SF21 cells. The infection is allowed to proceed for three to fourdays, allowing sufficient time for maximal production of the heterodimerprotein.

Recovery and Protein A Chromatographic Purification. At the conclusionof the infection phase of the bioreactor process the cells wereconcentrated in the bioreactor using a 10 ft² Millipore Prostak filter(0.65 micron) pore size. The cell-free permeate passing through thefilter was collected in a clean process vessel. At the conclusion of thefiltration operation the pH of permeate stream, containing the proteinproduct, was adjusted to 8.0 with 10N NaOH. The resultant precipitatewas removed by forcing the extract through a 0.8 micron depth filter(Sartorious), followed by a 0.2 micron filter. Sufficient 0.5M EDTAstock was added to give a final concentration of 5 mM. The filteredprotein solution was loaded onto a 10 cm diameter column containing100-200 mL of Pharmacia Protein A Sepharose 4 Fast Flow, equilibratedwith PBS. Protein A has a very high affinity for the Fc-Fc domain ofeach of the 3 recombinant protein products, allowing them to bind whileother proteins in the cell-free extract flow through the column. Afterloading the column was washed to baseline with PBS containing anadditional 350 mM NaCl. The IgG-Fc tagged proteins were eluted at lowpH, either with 0.5M acetic acid or with a decreasing pH gradient of0.1M citric acid and 0.2M disodium phosphate buffers. Tris base ordisodium phosphate was added to the eluted protein to avoid prolongedexposure to low pH conditions.

The pooled protein was diafiltered into PBS or HEPES buffer andderivitized with 1 mM iodoacetamide to protect the exposed sulfhydrylgroup on the free cysteine near the hinge region of each Fc domain. Thisprevents disulfide mediated aggregation of proteins. A 6 ft² Milliporespiral wound ultrafiltration membrane with nominal 30 kDa cutoff wasused to perform the buffer exchange. The total protein was determined byUV absorbance at 280 nm using the diafiltration buffer as a blank. Therelative amounts of heterodimer and two homodimer proteins weredetermined by SDS PAGE gel electrophoresis using a 6% Tris-Glycine gel(Novex). Gels were Coomassie-stained then transferred into destainsolution overnight. A Shimadzu scanning densitometer was used todetermine the relative intensity of the individual protein bands on theSDS PAGE gel. The peak area ratios are used to compute the fraction ofheterodimer and each of the homodimers in the column pool fractions.

Immobilized Metal Affinity Chromatographic Purification. The sixhistidine residues on the C-terminus of the GP130-Fc-His₆ fusion proteinprovides an excellent molecular handle for separation of theheterodimeric IL6 antagonist from the two homodimers. The imidazolegroup on each of the C-terminal histidines of the GP130-Fc-His₆ moietyhas a strong binding constant with several divalent metals, includingcopper, nickel, zinc, cobalt, iron and calcium. Since the IL6Rα-Fchomodimer has no C-terminal histidine residues, it clearly has thelowest affinity. The IL6Rα-Fc-GP130-Fc-His₆ heterodimer has a singlestand set six histidines giving it greater affinity for the metal, whilethe GP130-Fc-His₆ homodimer has two sets of six histidines each givingit the highest affinity of the three IgG tagged proteins to the metalaffinity column. Selective elution of the three proteins with increasingamounts of imidazole in the elution buffer therefore elutes the proteinsin the following order: 1. IL6Rα-Fc homodimers, 2. IL6Rα-Fc-GP130-Fc-Hisheterodimer, 3. GP130-Fc-His homodimers.

A 26 mm diameter column containing 100 mL of Pharmacia ChelatingSepharose Fast Flow was saturated with a solution of nickel sulfateuntil a significant green color is observed in the column eluate. Thecolumn is then washed with several column volumes of deionized water,then equilibrated with 50 mM HEPES, 40 mM imidazole, pH 8.0. The bindingof imidazole to the immobilized nickel results in a green to blue colorchange. Imidazole was added to the protein load to a final concentrationof 40 mM. Addition of imidazole to the protein load reduces the bindingof IL6Rα-Fc homodimer, increasing the surface area available for theremaining two species. After loading, the column was washed with severalcolumn volumes of 50 mM HEPES, 80 mM imidazole, pH 8.0 until a steadybaseline was reestablished. The heterodimer was selectively eluted with50 mM HEPES, 150 mM imidazole, pH 8.0 over several column volumes. Theprotein fractions were pooled and diafiltered into PBS as described inthe section above.

Example 4 Alternative Methods of Constructing Ligand Traps

As described above, receptor activation by CNTF, and analogously by IL-6and IL-11, follows an ordered sequence of binding events (FIG. 6). Thecytokine initially binds to its cognate Rα with low affinity (Kd=3 to 10nM); this is a required step—cells which do not express the cognate Rαdo not respond to the cognate cytokine. The cytokine•Rα complexassociates with the first signal transducing component, gp130, to form ahigh affinity complex (Kd in the order of 10 pM for theCNTF•CNTFRa•gp130 complex). This complex does not transduce signal, asit is the dimerization of the signal transducing components that bringsabout signaling (Stahl et al. 1994 J Neurobiology 25:1454-1466; Stahl etal. 1995 Science 267:1349-1353; Davis et al. 1993 supra; Stahl et al.1994 Science 263:92-95; Murakami et al. 1993 Science 260:1808-1810). Atleast in the case of IL-6, the cytokine•Rα•signal transducerheterotrimeric complex subsequently associates with another likecomplex, to form a hexameric complex (FIG. 6) (Ward et al. 1994 J BiolChem 269:23286-23289). The resulting dimerization of the signaltransducers—gp130 in the case of IL-6 (Murakami et al. 1993 supra) andIL-11, gp130 and LIFR in the case of CNTF (Davis et al. 1993supra)—brings about signal transduction.

The initial heterodimeric molecules made comprised a solubleRα-component linked to the extracellular domain of gp130. Thesemolecules were shown to mimic the high affinity cytokine•Rα•gp130complex and behave as a high affinity antagonist of their cognatecytokine (FIG. 7). To make these molecules, the extracellular domain ofgp130 was paired with the extracellular domain of the a-receptorcomponents for IL-6 and CNTF, IL-6Rα and CNTFRα respectively. To linkthe Rα with the extracellular domain of gp130, the soluble Rα-componentsand gp130 were fused to the Fc portion of human IgG1 to produce Rα-Fcand gp130-Fc respectively. The Fc domain was chosen primarily but notsolely because it naturally forms disulfide-linked dimers. Heterodimericmolecules comprising Rα-Fc•gp130-Fc were expressed, purified and shownto behave as highly potent antagonists of their cognate ligand.Furthermore, these molecules were found to be highly specific for theircognate cytokine since it is the choice of the α-receptor componentwhich specifies which cytokine is bound and trapped (there is nomeasurable binding of the cytokine to gp130 in the absence of theappropriate Rα).

Here we describe an extension of this technology which allows theengineering of different heteromeric soluble receptor ligand Traps whichby virtue of their design may have additional beneficial characteristicssuch as stability, Fc-receptor-mediated clearance, or reduced effectorfunctions (such as complement fixation). Furthermore, the technologydescribed should prove suitable for the engineering of any heteromericprotein in mammalian or other suitable protein expression systems,including but not limited to heteromeric molecules which employreceptors, ligands, and catalytic components such as enzymes orcatalytic antibodies.

Genetic engineering of heteromeric immunoglobulin heavy/light chainsoluble receptor-based ligand Traps for IL-6. The IL-6 Traps describedhere were engineered using human gp130, human IL-6 α-receptor (IL-6Ra),the constant region of the heavy chains (Cγ) of human IgG1 (Cγ1) (Lewiset al. 1993 J Immunology 151:2829-2838) or IgG4 (Cγ4) with or without ajoin-region (J), and the constant regions of kappa (κ) and lambda (λ)(Cheung et al. 1992 J Virology 66:6714-6720) light chains of humanimmunoglobulin (Ig), also with or without a different j-peptide (j).This design takes advantage of the natural ability of the Cg domain toheterodimerize with κ or λ light chains. The heterodimerization of Cgwith the light chain occurs between the CH1 domain of Cg and theconstant region of the light chain (C_(L)), and is stabilized bycovalent linking of the two domains via a single disulfide bridge. Wereasoned that, like the Fc domain of human IgG1, the combination of Cgwith C_(L) could be used to produce disulfide linked heteromericproteins comprised of the extracellular domain of gp130 on one chain andthe extracellular domain of IL-6Rα on the other chain. Like theirFc-based counterparts, such proteins were postulated to be high affinityligand Traps for IL-6 and as a result to inhibit the interaction of IL-6with the native receptor on IL-6-responsive cells, thus functioning asIL-6 antagonists. Furthermore, constructs employing the full length Cgregion would, much like antibodies, form homodimers of the Cg chain,giving rise to antibody-like molecules comprising of two “light chains”and two “heavy chains” (FIG. 8). The potential advantage of this designis that it may more closely mimic the IL-6IL•-6Rα•gp130 complex and maydisplay a higher affinity for the ligand than comparable singleheterodimers. An additional design is incorporated by using truncatedversions of Cγ, comprised only of the C_(H)1 domain. These will formheterodimeric molecules with receptor-k fusion proteins, and will thusresemble the Fab fragment of antibodies.

All the soluble receptor-Ig chimeric genes may be engineered in plasmidvectors including, but not limited to, vectors suitable for mammalianexpression (COS monkey kidney cells, Chinese Hamster Ovary cells (CHO),and ras-transformed fibroblasts (MG-ras) and include a Kozak sequence(CGC CGC CAC CAT GGT G) (SEQ ID NO: 3) at the beginning of each chimericgene for efficient translation. Engineering was performed using standardgenetic engineering methodology. Each construct was verified by DNAsequencing, mammalian expression followed by western blotting withsuitable antibodies, biophysical assays that determine ligand bindingand dissociation, and by growth inhibition assays (XG-1, as describedlater). Since the domains utilized to engineer these chimeric proteinsare flanked by appropriate restriction sites, it is possible to usethese domains to engineer other chimeric proteins, including chimerasemploying the extracellular domains of the receptors for factors such asIL-1, IL-2, IL-3, IL-4, IL-5, GM-CSF, LIF, IL-11, IL-15, IFNg, TGFb, andothers. The amino acid coordinates for each component utilized in makingthe IL-6 Traps are listed below (Note: numbering starts with theinitiating methionine as 1; long sequences are listed using the singleletter code for the twenty amino acids):

(a) Constructs employing human gp130: (i) gp130-Cγ1 was engineered byfusing in frame the extracellular domain of gp130 (amino acids 1 to 619)to a Ser-Gly bridge, followed by the 330 amino acids which comprise Cγ1and a termination codon (SEQ ID NO: 9).

(ii) gp130-J-Cγ1 was engineered in the same manner as gp130-Cγ1 exceptthat a J-peptide (amino acid sequence: GQGTLVTVSS) (SEQ ID NO: 4) wasinserted between the Ser-Gly bridge and the sequence of Cγ1 (SEQ ID NO:9).

(iii) gp130D3fibro-Cγ1 was engineered by fusing in frame theextracellular domain of gp130 without its three fibronectin-like domains(SEQ ID NO: 10). The remaining part of this chimeric protein isidentical to gp130-Cγ1.

(iv) gp130-J-C_(H)1 was engineered in a manner identical for thatdescribed for gp130-Cγ1, except that in place of the Cγ1 region only theC_(H)1 part of Cγ1 has been used (SEQ ID NO: 11). The C-terminal domainof this construct includes the part of the hinge that contains thecysteine residue responsible for heterodimerization of the heavy chainof IgG with a light chain. The part of the hinge that contains the twocysteines involved in Cγ1 homodimerization has been deleted along withthe C_(H)2 and C_(H)3 domains.

(v) gp130-Cγ4 was engineered in a manner identical to that described forgp130-Cγ1, except that Cγ4 was used in place of Cγ1 (SEQ ID NO: 12). Inaddition, an RsrII DNA restriction site was engineered at the hingeregion of the Cg4 domain by introducing two silent base mutations. TheRsrsII site allows for other desired genetic engineering manipulations,such as the construction of the C_(H)1 equivalent of gp130-Cγ4.

(vi) gp130-κ was engineered in a manner identical to that described forgp130-Cg1, except that the constant region of the κ light chain of humanIg was used in place of Cγ1 (SEQ ID NO: 13).

(vi) gp130-J-k was engineered in a manner identical to that describedfor gp130-J-κ, except that a j-peptide (SEQ ID NO: 5) was insertedbetween the Ser-Gly bridge and the κ-region.

(viii) gp130-l was engineered in a manner identical to that describedfor gp130-Cγ1, except that the constant region of the λ light chain(Cheung et al. 1992 supra) of human Ig was used in place of Cγ1 (SEQ IDNO: 14).

(b) Constructs employing human IL-6Rα: (i) IL6Rα-Cγ1 was engineered byfusing in frame amino acids 1 to 358 of IL-6Ra (Yamasaki et al. 1988Science 241:825-828), which comprise the extracellular domain of IL-6Rα(SEQ ID NO: 15), to an Ala-Gly bridge, followed by the 330 amino acidswhich comprise Cγ1 and a termination codon.

(ii) IL6Rα-κ was engineered as described for IL6Rα-Cγ1, except that theκ-domain (SEQ ID NO: 13) utilized for gp130-κ was used in place of Cγ1.

(iii) IL6Rα-j-k was engineered as described for IL6Rα-κ except that thej-peptide described for gp130-j-κ was placed between the Ala-Gly bridgeand the κ-domain.

(iv) Three additional constructs, IL6Rα313-Cγ1, IL6Rα313-κ, andIL6Rα313-j-κ, were engineered as using a truncated form of IL-6Rαcomprised of amino acids 1 to 313 (SEQ ID NO:16). Each of theseconstructs were made by fusing in frame IL6Rα313 with a Thr-Gly bridgefollowed by the Cγ1, κ-, and j-κ-domains described above. Theseconstructs were engineered in order to complement thegp130D3fibro-derived constructs.

Expression and purification of ligand Traps. To produce covalentlylinked heterodimers of soluble gp130 and soluble IL-6Rα, gp130-Igchimeric proteins were co-expressed with appropriate IL-6Rα-Ig chimericproteins in complementing pairs. Co-expression was achieved byco-transfecting the corresponding expression vectors into suitablemammalian cell lines, either stably or transiently. The resultingdisulfide-linked heterodimers were purified from conditioned media byseveral different methods, including but not limited to affinitychromatography on immobilized Protein A or Protein G, ligand-basedaffinity chromatography, ion exchange, and gel filtration.

An example of the type of methods used for purification of a heavy/lightreceptor fusion protein is as follows: gp130-Cγ1•IL-6Rα-k was expressedin COS cells by co-transfecting two different vectors, encodinggp130-Cγ1 and IL-6Rα-κ respectively. Serum-free conditioned media (400ml) were collected two days post-transfection and Cγ1-bearing proteinswere purified by affinity chromatography over a 1 ml Protein A Sepharose(Pharmacia). The material generated in this step was further purified bya second affinity chromatography step over a 1 ml NHS-activatedSepharose (Pharmacia) which was derivatized with recombinant human IL-6,in order to remove gp130-Cγ1 dimer from gp130-Cγ1•IL-6Rα-k complexes(the gp130-Cγ1 dimer does not bind IL-6). Proteins generated by thismethod were more than 90% pure, as evidenced by SDS-PAGE followed bysilver-staining (FIG. 17). Similar protocols have been employedsuccessfully towards the purification of other heavy/light receptorheterodimers.

Biological activity of immunoglobulin heavy/light chain receptor fusionantagonists. The purified ligand Traps were tested for their ability tobind IL-6 in a variety of different assays. For example, thedissociation rate of IL-6 bound to the ligand Trap was measured inparallel with the dissociation rate of IL-6 from the anti-IL-6monoclonal neutralizing antibody B-E8 (Brochier et al. 1995 Int JImmunopharmacology 17:41-48). An example of this type of experiment isshown in FIG. 18. In this experiment 20 pM ¹²⁵I-IL-6 (1000 μCi/mmol;Amersham) was preincubated with 500 pM of either gp130-Cg1•IL-6Rα-κ ormAb B-E8 for 20 hours. At this point a 1000-fold excess (20 nM) of“cold” IL-6 was added. Periodically, aliquots of the reaction wereremoved, the ligand Trap or B-E8 were precipitated with ProteinG-Sepharose, and the number of cpm of ¹²⁵I-IL-6 that remained bound wasdetermined. Clearly, the dissociation rate of human ¹²⁵I-IL6 from theligand Trap was very slow—after three days, approximately 75% of theinitial counts were still bound to the ligand Trap. In contrast, lessthan 5% of the counts remained associated with the antibody after threedays. This result demonstrates that the dissociation rate of the ligandfrom these ligand Traps is very slow.

In a different set of experiments the ability of the ligand Traps tomultimerize in the presence of ligand was tested. An example of this isshown in FIGS. 19A-19B. IL-6-induced association of gp130-Fc•IL-6Rα-Fcwith gp130-C_(H)1•IL-6Rα-κ was determined by testing whethergp130-C_(H)1•IL-6Rα-κ, which does not by itself bind Protein A, could beprecipitated by Protein A-Sepharose in the presence ofgp130-Fc•IL-6Rα-Fc in an IL-6-depended manner (SEQ ID NO: 9).Precipitation of gp130-C_(H)1•IL-6Rα-κ by Protein A-Sepharose wasdetermined by western blotting with an anti-kappa specific HRPconjugate, which does not detect gp130-Fc•IL-6Rα-Fc.gp130-C_(H)1•IL-6Rα-κ could be precipitated by Protein A-Sepharose onlywhen both gp130-Fc•IL-6Rα-Fc and IL-6 were present. This resultconclusively indicates that IL-6 can induce ligand Trap multimerization,and further indicate that the ligand Trap can mimic the hexamericcytokine•Rα•signal transducer complex (FIG. 1). Ligand-inducedmultimerization may play a significant role in the clearance ofcytokine•ligand Trap complexes in vivo.

The biological activity of the different ligand Traps may be furthertested in assays which measure ligand-depended cell proliferation.Several cell proliferation assays exist for IL-6 and they employ celllines such as B9, CESS, or XG-1. An example of this type of assay usingthe XG-1 cell line is presented below: XG-1 is a cell line derived froma human multiple myeloma (Zhang et al. 1994 Blood 83:3654-3663). XG-1depends on exogenously supplied human IL-6 for survival andproliferation. The EC₅₀ of IL-6 for the XG-1 line is approximately 50pmoles/ml. The ability of several different IL-6 Traps to blockIL-6-depended proliferation of XG-1 cells was tested by incubatingincreasing amounts of purified ligand Traps with 50 pg/ml IL-6 in XG-1cultures. The ligand Traps which were tested had been expressed andpurified by methods similar to those described above. All of the ligandTraps tested were found to inhibit IL-6-dependent proliferation of XG-1in a dose dependent manner (FIG. 20). Of the five different Traps testedgp130-Cg1•IL-6Rα-κ was the most active and essentially display the sameneutralizing activity towards IL-6 as the antibody B-E8. As little as a10-fold molar excess of either gp130-Cg1•IL-6Rα-κ or B-E8 completelyblocked the activity of IL-6 (a reading of A570-650=0.3 AU correspondsto no proliferation of the XG-1 cells). At a 100-fold molar excess allof the ligand Traps tested completely blocked the activity of IL-6. Thisobserved inhibition is highly selective as neither a gp130-Fc•CNTFRα-Fcligand Trap which blocks CNTF activity, nor gp130-Fc homodimer exhibitany blocking activity towards IL-6 even when used at a 1000-fold molarexcess over IL-6 (data not shown). This data demonstrates that theheteromeric immunoglobulin heavy/light chain receptor-based ligand Trapsfunction as selective high affinity antagonists of their cognate ligand.

Example 5 Cloning of Fusion Polypeptide Components

The extracellular domains of the human cytokine receptors were obtainedby standard PCR techniques using tissue cDNAs (CLONTECH), cloned intothe expression vector, pMT21 (Genetics Institute, Inc.), and thesequences were sequenced by standard techniques using an ABI 373A DNAsequencer and Taq Dideoxy Terminator Cycle Sequencing Kit (AppliedBiosystems, Inc., Foster City, Calif.). For the IL-4Rα nucleotides 241through 868 (corresponding to the amino acids 24-231) from the Genbanksequence, X52425, were cloned. For the IL-2Rg, nucleotides 15 through776 (corresponding to amino acids 1-233) from the Genbank sequence,D11086, were cloned. For the IL-6Rα, nucleotides 52 through 1044(corresponding to the amino acids 1-331) from the Genbank sequence,X52425, were cloned. For gp130, nucleotides 322 through 2112(corresponding to the amino acids 30-619) from the Genbank sequence,M57230, were cloned. For the IL-1RAcP, nucleotides 1 through 1074(corresponding to the amino acids 1-358) from the Genbank sequence,AB006357, were cloned. For the IL-1RI, nucleotides 55 through 999(corresponding to the amino acids 19-333) from the Genbank sequence,X16896, were cloned.

Example 6 Production of Fusion Polypeptides (Cytokine Traps)

The nucleotide sequences encoding the cytokine Traps were constructedfrom the individual cloned DNAs (described supra) by standard cloningand PCR techniques. In each case, the sequences were constructed inframe such that the sequence encoding the first fusion polypeptidecomponent was fused to the sequence encoding the second fusionpolypeptide component followed by an Fc domain (hinge, CH2 and CH3region of human IgG1) as the multimerizing component. In some casesextra nucleotides were inserted in frame between sequences encoding thefirst and second fusion polypeptide components to add a linker regionbetween the two components: Trap 424 (SEQ ID NO: 17); Trap 412 (SEQ IDNO:23); and Trap 569 (SEQ ID NO:27).

For the IL-4 Traps, 424 (SEQ ID NO: 17), 603 (SEQ ID NO: 19) and 622(SEQ ID NO:21), the IL-2Rγ component is 5′, followed by the IL4Rαcomponent and then the Fc component. For the IL-6 Traps, 412 (SEQ ID NO:23) and 616 (SEQ ID NO:25), the IL-6Rα component is 5′ followed by thegp130 component and then the Fc domain. For the IL-1 Trap 569 (SEQ IDNO: 27), the IL-1RAcP component is 5′ followed by the IL-1RI componentand then the Fc domain. The final constructs were cloned into themammalian expression vector pcDNA3.1 (STRATAGENE).

In the 569 sequence (SEQ ID NO: 27), nucleotides 1-1074 encode theIL1RAcP component, nucleotides 1075-1098 encode a linker region,nucleotides 1099-2043 encode the IL1RI component and nucleotides2044-2730 encode the Fc domain.

In the 412 sequence (SEQ ID NO: 23), nucleotides 1-993 encode the IL6Rαcomponent, nucleotides 994-1023 encode a linker region, nucleotides1024-2814 encode the gp130 component and nucleotides 2815-3504 encodethe Fc domain.

In the 616 sequence (SEQ ID NO: 25), nucleotides 1-993 encode the IL6Rαcomponent, nucleotides 994-2784 encode the gp130 component andnucleotides 2785-3474 encode the Fc domain.

In the 424 (SEQ ID NO: 17) and 622 (SEQ ID NO: 21) sequences,nucleotides 1-762 encode the IL2Rγ component, nucleotides 763-771 encodea linker region, nucleotides 772-1395 encode the IL4Rα component andnucleotides 1396-2082 encode the Fc domain.

Finally, in the 603 sequence (SEQ ID NO: 19), nucleotides 1-762 encodethe IL2Rg component, nucleotides 763-1386 encode the IL4Rα component andnucleotides 1387-2073 encode the Fc domain.

DNA constructs were either transiently transfected into COS cells orstably transfected into CHO cells by standard techniques well known toone of skill in the art. Supernatants were collected and purified byProtein A affinity chromatography and size exclusion chromatography bystandard techniques. (See Harlow &Lane, Antibodies—A Laboratory Manual,Cold Spring Harbor Laboratory, 1988).

Example 7 IL-4 Bioassay Protocol Using TF-1 (ATCC) Cells

MTT Dye Solution: MTT(3-[4,5-Dimethylthiazole-2-yl]) (Sigma catalog#M2128) Working concentration: Dissolve 5 mg of anhydrous MTT in 200 mlPBS without Ca⁺², Mg⁺². Sterile filter and store aliquoted at −20° C.

Solubilization Solution: For 1000 ml, combine 100 g SDS, 950 ml dH₂O, 50ml Dimethyl Formamide, and 850 μl concentrated HCl. Filter sterilizewith a 0.45 μm filter unit. Store at room temperature.

TF-1 cell Growth Medium: RPMI 1640, 10% FBS, Pen/Strep, 2 mM L-glutamine

Other: 0.4% Trypan Blue Stain, sterile tubes for dilutions, sterile 96well cell culture plates (Falcon #3072), hemacytometer, centrifuge,ELISA plate reader, multichannel pipet for 15, 25, 50 and 100 μl volume,sterile reagent reservoirs, sterile pipet tips, gloves.

Assay Protocol A. Preparation of Assay plates. 1. Prepare sterile 96well tissue culture plates to contain 50 μl of growth medium per wellwith various concentrations of IL-4 and 10 nM IL-4 antagonist. This canbe done by preparing a working dilution of IL-4 that is 4 times thehighest concentration to be assayed. In separate tubes, do a two-foldserial dilution of the IL-4. Add 25 μl of each dilution to one rowacross the plate (i.e. row A gets highest concentration, row G getslowest concentration). Add 25 μl of growth medium without IL-4 to row H.Prepare the antagonists to be tested by making a stock that is 4 timesthe final concentration. Add 25 μl to a triplicate set of IL-4containing wells (columns 1,2,3, A through H). Be sure to includeantagonist in row H. 2. As a positive control, leave one set with noantagonist. These wells will contain IL-4 and media only. 3. Incubatethe plate for 1-2 hours at 37° C. in a humidified 5% CO₂ incubatorbefore preparing cells to be used for assay.

B. Preparation of Cells. 4. Wash cells twice by centrifugation in assaymedium free of growth factor. 5. Determine cell number and trypan blueviability and suspend cells to a final concentration of 8×10⁵/ml inassay medium. 6. Dispense 50 μl of the cell suspension (40,000 cells)into all wells of the plates. Total volume should now be 100 μl/well. 7.Incubate the plate at 37° C. for 68 hours in a humidified 5% CO₂incubator.

C. Color Development. 8. After incubating for 68 hours, add 15 μl of theMTT dye solution to each well. 9. Incubate the plate at 37° C. for 4hours in a humidified 5% CO₂ incubator. 10. After 4 hours, add 100 μl ofthe solubilization solution to each well. Allow the plate to standovernight in a sealed container to completely solubilize the formazancrystals. 11. Record the absorbance at 570/650 nm.

Results. FIG. 27 shows that an IL-4 Trap designated 4SC375, which is afusion polypeptide of IL-2Rg-scb-IL4Ra-FcΔC1, is several orders ofmagnitude better as an IL-4 antagonist than IL4RαFcΔC1 alone in the TF1cell bioassay. FIG. 28 shows that the IL-4 Trap designated 4SC375 showsantagonistic activity in the TF1 cell bioassay equivalent to an IL-4Trap designated 4SC424 which is a fusion polypeptide ofIL-2Rγ-IL4Rα-FcΔC1 having the IL-2Rγ component flush with the IL-4Rαcomponent.

Example 8 IL-6 Bioassay Protocol Using XG-1 Cells

MTT dye solution and solubilization solution, assay protocol, cellpreparation and color development were as described above with IL-6 usedinstead of IL-4. Assay Medium: RPMI 1640, 10% FBS, Pen/Strep, 2 mML-glutamine, 50 μM mercapto-ethanol.

Results. FIG. 29 shows that the IL6 Trap (6SC412 IL6R-scb-gpx-FcΔC1)(SEQ ID NO: 23 and 24) is a better antagonist of IL-6 in the XG1bioassay than the neutralizing monoclonal antibody to human IL-6-BE8.

Example 9 MRC5 Bioassay for IL-1 Traps

MRC5 human lung fibroblast cells respond to IL-1 by secreting IL-6 andthus were utilized to assay the ability of IL-1 Traps to block theIL-1-dependent production of IL-6. IL1 Trap 1SC569 was tested againstIL-1-RI.Fc which is the extracellular domain of the IL-1 Type I receptorfused to an Fc domain.

MRC5 cells are suspended at 1×10⁵ cells per ml in medium and 0.1 ml ofcells are plated (10,000 cells per well) into the wells of a 96 welltissue culture plate. Plates are incubated for 24 hours at 37° C. in ahumidified 5% CO₂ incubator.

IL-1 Trap and recombinant human IL-1 at varying doses are pre-incubatedin a 96 well tissue culture dish and incubated for 2 hours at 37° C. 0.1ml of this mixture is then added to the 96 well plate containing theMRC5 cells such that the final concentration of IL-1 Trap is 10 nM andthe final concentrations of the IL-1 ranges from 2.4 pM to 5 nM. Controlwells contain Trap alone or nothing.

Plates are then incubated at 37° C. for 24 hours in a humidified 5% CO₂incubator. Supernatant is collected and assayed for levels of IL-6 usingR&D Systems Quantikine Immunoassay Kit according to the manufacturer'sinstructions.

Results. FIG. 30 shows that the Trap 569 (SEQ ID NO:28) is able toantagonize the effects of IL-1 and block the IL-6 production from MRC 5cells upon treatment with IL-1. At a concentration of 10 nM, the Trap569 is able to block the production of IL-6 up to an IL-1 concentrationof 3 nM. In contrast, the IL-1RI.Fc is a much poorer antagonist of IL-1.It is only able to block the effects of IL-1 up to about 10-20 pM. Thus,the Trap 569 is approximately 100× better at blocking IL-1 thanIL1RI.Fc.

Example 10 Construction of IL-13/IL-4 Single Chain Traps

1. To create the IL-13/IL-4 dual Trap designated IL-4Rα.IL-13Rα1.Fc, thehuman IL-4Rα extracellular domain (corresponding to nucleotides 1-693 ofSEQ ID NO: 29) and the human IL-13Ra1 extracellular domain(corresponding to nucleotides 700-1665 of SEQ ID NO: 29) were amplifiedby standard PCR techniques and ligated into an expression vector pMT21which contained the human Fc sequence (corresponding to nucleotides1671-2355 of SEQ ID NO: 29), thus creating a fusion protein consistingof the IL-4Rα, IL-13Rα1, and the hinge, CH2 and CH3 region of human IgG1from the N to C terminus. In addition, a two amino acid linker(corresponding to nucleotides 694-699 of SEQ ID NO: 30) with the aminoacid sequence SerGly was constructed in frame between the IL-4Rα and theIL-13Rα1 and a two amino acid linker (corresponding to nucleotides1666-1671 of SEQ ID NO: 30) with the amino acid sequence ThrGly wasconstructed in frame between the IL-13Rα1 and the Fc portion. Allsequences were sequence-verified by standard techniques. TheIL-4Rα.IL-13Rα1.Fc coding sequence was then subcloned into theexpression vector pcDNA3.1 (Stratagene) using standard molecular biologytechniques.

2. To create the IL-13/IL-4 dual Trap designated IL-13Rα1.IL-4Rα.Fc, theIL-13Rα1 extracellular domain (corresponding to nucleotides 1-1029 ofSEQ ID NO: 31) and the human IL-4Rα (corresponding to nucleotides1060-1692 of SEQ ID NO: 31) were amplified by standard PCR techniquesand ligated into the expression vector pJFE14, which contains the humanFc sequence (corresponding to nucleotides 1699-2382 of SEQ ID NO: 31) tocreate a fusion protein consisting of the IL-13Rα1, IL-4Rα, and thehinge, CH2 and CH3 region of human IgG1 from the N to C terminus. Inaddition, a ten amino acid linker with the amino acid sequenceGlyAlaProSerGly-GlyGlyGlyArgPro (SEQ ID NO: 6) (corresponding tonucleotide 1030-1059 of SEQ ID NO: 31) was constructed in frame betweenthe IL-13Rα1 and the IL-4Rα and a two amino acid linker (correspondingto nucleotides 1693-1698 of SEQ ID NO: 31) with the amino acid sequenceSerGly was constructed in frame between IL-4Rα and the Fc portion. Allsequences were sequence-verified using standard techniques. The codingsequence of IL-13Rα1.IL-4Rα.Fc was then subcloned into the expressionvector pcDNA3.1 (Stratagene) using standard molecular biologytechniques.

Example 11 Expression of IL-4Rα.IL-13Rα1.Fc andIL-13Rα1.IL-4Rα.Fc.IL-4Rα.

Large scale (1 L) cultures of the pCAE801 (the DNA vector constructencoding IL-4Rα.IL-13Rα1.Fc) and pCAE802 (the DNA plasmid constructencoding IL-13Rα1.IL-4Rα.Fc) in DH10B cells were grown overnight inLB+ampicillin and the plasmid DNA was extracted using a Qiagen EndofreeMega Kit following the manufacturer's protocol. The concentration of thepurified plasmid DNA was determined in a UV spectrophotometer andfluorometer. The plasmid DNA was also verified by digestion of aliquotswith BbsI, XmnI and NcoI restriction enzymes. All restriction enzymedigest fragments corresponded to the predicted sizes in a 1% agarosegel.

Forty 15 cm petri plates were seeded with CHO-K1/E1A cells at a densityof 4×10⁶ cells/plate. Plating media was Gibco Ham's F-12 w/10% HycloneFetal Bovine Serum (FBS)+penicillin/streptomycin and supplemented withglutamine. The following day each plate was transfected with 6 μg ofpCAE801, or pCAE802, using Gibco Optimem and Gibco Lipofectamine in 12ml volume, following the manufacturer's protocol. Four hours afteradding the transfection mix to the cells 12 ml/plate of Optimem w/ 10%FBS was added. Plates were incubated at 37° C. in a 5% CO₂ incubatorovernight. The following day the media was removed from each plate and25 ml expression media (Gibco CHO-S-SFM II w/ glutamine+1 mM sodiumbutyrate) was added. The plates were incubated at 37° C. for 3 days.

After 3 days of incubation the media was removed from each plate andcentrifuged at 400 rpm in a swinging bucket rotor to pellet cells. Thesupernatant was decanted into sterile 1 L bottles and expressed proteinwas purified as described infra.

Example 12 Purification of IL-4Rα.IL-13Rα1.Fc and IL-13Rα1.IL-4Rα.FcProtein

1. Purification of IL-4Ra.IL-13Ra1.Fc. Human IL-4Ra.IL-13Ra1.Fc wastransiently expressed in CHO cells and supernatants were harvested fromplate transfections as described supra. Expression of the secretedprotein was determined by a sandwich ELISA using goat anti-hIgG (γ chainspecific; Sigma 1-3382) and goat anti-hIgG (Fc specific)-FITC conjugate(Sigma F9512) capture and report antibodies, respectively. The yieldranged from 5.8 to 9.2 mg (average of 7.5 mg) per liter of conditionedmedia. Complete™ protease inhibitor tablets (Roche Diagnostics Corp.)were dissolved into the media (1 tablet/L). The conditioned media wassterile filtered (0.22 μm pore size) prior to loading onto apre-equilibrated, 5 mL HiTrap® Protein A affinity column (AmershamPharmacia Biotech) in Dulbecco's PBS buffer (Life Technologies), pH 7.4at 4° C. The flow rate was ˜1-2 mL/min. The column was extensivelywashed with PBS buffer to remove nonspecifically bound proteins from thecolumn. IL-4Rα.IL-13Rα1.Fc was eluted using 20 mM sodium citrate, 150 mMNaCl, pH 3.5. The eluate was immediately neutralized by titrating with 1M Tris-OH. The fractions containing protein were pooled and immediatelydialyzed in PBS buffer, pH 7.4 at 4° C. The recovery from Protein Apurification was 6.8 mg (73%). IL-4Rα.IL-13Rα1.Fc was further purifiedby size exclusion chromatography using a superose 6 column (25 mL bedvolume; Amersham Pharmacia Biotech) pre-equilibrated in PBS, 5% v/vglycerol, pH 7.4 at ambient temperature. The flow rate was 0.5 mL/min.Protein fractions were assessed from a Coomassie stained non-reduced andreduced SDS-PAGE (Novex NuPAGE 4-12% Bis-Tris gels). Fractions wereconservatively pooled to reduce the amount of aggregated protein. Theoverall yield was 51% (4.4 mg) with a purity of 97% as judged bySDS-PAGE. Purified IL-4Rα.IL-13Rα1.Fc was analyzed by non-reduced andreduced SDS-PAGE (4-12% Bis-Tris), analytical size exclusionchromatography (Tosohaas TSKG4000SWXL), N-terminal sequencing, andimmunoblotting with goat anti-hIgG-HRP conjugate (Promega W403B), andalso mouse monoclonal anti-hIL-4R(R&D MAB230) followed by anti-mIgG-HRPconjugate (Promega W402B) as the secondary antibody.

2. Purification of IL-13Rα1.IL-4Rα.Fc. Human IL-13Rα1.IL-4Rα.Fc wastransiently expressed in CHO cells and supernatants were harvested fromplate transfections as described supra. Expression of the secretedprotein was determined by a sandwich ELISA using goat anti-hIgG (γ chainspecific; Sigma 1-3382) and goat anti-hIgG (Fc specific)-FITC conjugate(Sigma F9512) capture and report antibodies, respectively. The yield was8.8 mg per liter of conditioned media. Complete™ protease inhibitortablets (Roche Diagnostics Corp.) were dissolved into the media (1tablet/L). The conditioned media was sterile filtered (0.22 μm poresize) prior to loading onto a pre-equilibrated, 5 mL HiTrap® Protein Aaffinity column (Amersham Pharmacia Biotech) in Dulbecco's PBS buffer(Life Technologies), pH 7.4 at 4° C. The flow rate was ˜1-2 mL/min. Thecolumn was extensively washed with PBS buffer to remove nonspecificallybound proteins from the column. IL-13Ra1.IL-4Ra.Fc was eluted using 20mM sodium citrate, 150 mM NaCl, pH 3.5. The eluate was immediatelyneutralized by titrating with 1 M Tris-OH. The fractions containingprotein were pooled and immediately dialyzed in PBS buffer, pH 7.4 at 4°C. The recovery from Protein A purification was 3.8 mg (43%).IL-13Rα1.IL-4Rα.Fc was further purified by size exclusion chromatographyusing a superose 6 column (25 mL bed volume; Amersham Pharmacia Biotech)pre-equilibrated in PBS, 5% v/v glycerol, pH 7.4 at ambient temperature.The flow rate was 0.5 mL/min. Protein fractions were assessed from aCoomassie stained non-reduced and reduced SDS-PAGE (Novex NuPAGE 4-12%Bis-Tris gels). Fractions were conservatively pooled to reduce theamount of aggregated protein. The overall yield was 17% (1.5 mg) with apurity of 95% as judged by SDS-PAGE. Purified IL-13Rα1.IL-4Rα.Fc wasanalyzed by non-reduced and reduced SDS-PAGE (4-12% Bis-Tris),analytical size exclusion chromatography (Tosohaas TSKG4000SWXL),N-terminal sequencing, and immunoblotting with goat anti-hIgG-HRPconjugate (Promega W403B), and also mouse monoclonal anti-hIL-4Rα (R&DMAB230) followed by anti-mIgG-HRP conjugate (Promega W402B) as thesecondary antibody.

Example 13 Blocking of IL-4Rα.IL-13Rα1.Fc and IL-13Rα1.IL-4Rα.Fc

TF1 Bioassay. TF1 cells were maintained in growth media (10 ng/mlGM-CSF, RPMI 1640, 10% FBS, L-glutamine, Penicillin, Streptomycin). Forthe bioassay, cells were washed 2 times in assay media (as above butwithout GM-CSF) and then plated at 2×10⁵ cells in 50 μl of assay media.The purified IL-4Ra.IL-13Rα1.Fc and IL-13Rα1.IL-4Rα.Fc proteins werediluted into assay media at a concentration of 40 nM. 25ul of each ofthe Traps was added to the cells. Either IL-13 or IL-4 were diluted to40 nM in assay media and then 2-fold dilution series in assay media weremade. 25 μl of either IL-13 or IL-4 was then added to the wellscontaining the cells and the Traps. Cells were then incubated at 37° C.,5% CO₂ for ˜70 hrs. The extent of TF1 cell proliferation was measured bythe MTS assay according to the manufacturer's protocol (Promega, Inc.).

Results. The ability of the IL-4Rα.IL-13Rα1.Fc and IL-13Rα1.IL-4Rα.FcTraps to block both human IL-13 and human IL-4 activity was measured inthe TF1 bioassay described supra. IL-13 stimulates proliferation of TF1cells, with half-maximal growth at a concentration of 0.2 nM. Additionof either IL-4Rα.IL-13Rα1.Fc or IL-13Rα1.IL-4Rα.Fc Trap at aconcentration of 10 nM blocks IL-13-induced growth up to ˜2 nM (FIG.33). At an IL-13 concentration of ˜4-5 nM the growth of TF1 cells isinhibited by 50%. TF1 cells are more sensitive to IL-4, which stimulatestheir proliferation with half-maximal growth at ˜0.02 nM. Addition ofeither IL-4Rα.IL-13Rα1.Fc or IL-13Rα1.IL-4Rα.Fc at a concentration of 10nM blocks IL-4-induced growth up to ˜1 nM (FIG. 34). At an IL-4concentration of ˜3-4 nM the growth of TF1 cells is inhibited by 50%.These results show that both IL-4Rα.IL-13Rα1.Fc and IL-13Rα1.IL-4Rα.Fccan block the ability of both IL-13 and IL-4 to stimulate cellularresponses.

Example 14 Blocking of Injected IL-1 by IL-1 Trap In Vivo

IL-1 is a pro-inflammatory cytokine. Systemic administration of IL-1 hasbeen shown to elicit acute responses in animals, including transienthyperglycemia, hypoinsulinemia, fever, anorexia, and increased serumlevels of interleukin-6 (IL-6). Since mice are responsive to both murineand human IL-1, human IL-1 can be used and in vivo binding effects ofhuman specific IL-1 antagonists can be evaluated. This acute mouse modelwas used to determine the ability of a human IL-1 Trap to antagonize thein vivo effects of exogenously administered human IL-1. This provides arapid indication of in vivo efficacy of the human IL-1 Trap and can beused as an assay to help molecule selection.

Experimental Design: Mice were given subcutaneous injections of humanIL-1 (0.3 μg/kg). Twenty-four hours prior to human IL-1 injection, theanimals were pre-treated with either vehicle or 150-fold molar excess ofhuman IL-1 Trap (0.54 mg/kg). Two hours prior to sacrifice (26 hrs), themice were given a second injection of human IL-1 (0.3 μg/kg). Bloodsamples were collected at various time points and sera were assayed forIL-6 levels.

Results. Exogenous administration of human IL-1 resulted a dramaticinduction of serum IL-6 levels. At 150-fold molar excess, the human IL-1Trap completely blocked the IL-6 increase (FIG. 35). Furthermore, theeffects of the human IL-1 Trap persisted for at least another 24 hours,preventing an IL-6 increase even when IL-1 was re-administered (FIG.35). Such long-lasting efficacy suggests that daily injection of an IL-1Trap may not be necessary for chronic applications.

In a separate experiment, IL-1ra at 150-fold or 750-fold molar excessdid not significantly block IL6 induction. Therefore, in this paradigm.IL-1 Trap appears to be a better blocker of IL-1 activity (see FIG. 50).

Example 15 Evaluating the Ability of an IL-4 Trap to Block thePhysiological Responses to Human IL-4 in Cynomologus Monkeys

Systemic administration of human IL-4 elicits systemic responses inCynomologus monkeys (Gundel et al., 1996). Thus, the effectiveness ofthe IL-4 Trap in blocking human IL-4 can be demonstrated by measuringthese responses.

Experimental Design: The experiment consisted of 3 parts: humanIL-4+vehicle (part 1), human IL-4+IL-4 Trap (part 2), and humanIL-4+vehicle (part 3). Human IL-4 (25 μg/kg) was injected subcutaneouslytwice daily for 4 days and IL-4 Trap (8 mg/kg) and vehicle were givenintravenously daily for 5 days, beginning 1 day prior to human IL-4administration. Whole blood was collected daily for flow cytometryanalysis for CD16 and plasma was obtained to assay for the cytokinemonocyte chemotactic protein 1 (MCP-1). CD16 and MCP-1 are markers ofIL-4-mediated inflammation in both humans and monkeys.

Results. In the presence of human IL-4, MCP-1 increased 2.5-fold and wassignificantly blocked by the IL-4 Trap (FIG. 36A). Similarly, thedecrease in the percent of CD16 positive lymphocytes in peripheral bloodwas attenuated by the IL-4 Trap (FIG. 36B). After a rest period, themonkeys were re-injected with human IL-4 and the responsiveness of theanimals to human IL-4 was re-confirmed (FIGS. 36A and 36B), suggestingthat inhibition of the MCP-1 and CD 16 responses is specificallymediated by the IL-4 Trap.

Example 16 The Effects of IL-4 Trap on IL-4-Induced IgE Secretion

It has been shown that injection of anti-mouse IgD antibody stimulatesan IL-4-mediated IgE increase in normal mice. This model has been widelyused to evaluate IL-4 antagonists, such as soluble IL-4 receptor andanti-IL-4 monoclonal antibodies (Sato et al., 1993). We decided to usethis model to evaluate the ability if the IL-4 Trap to blockIL-4-mediated increases of IgE.

Experimental design: BALB/C mice injected with anti-mouse IgD (100μl/mouse, s.c.) were randomly divided into 3 groups. Each received (ondays 3-5) either vehicle, murine IL-4 Trap (1 mg/kg, s.c.), or amonoclonal antibody to mouse IL-4 (1 mg/kg, s.c.). Serum was collectedat various time points and assayed for IgE levels.

Results. Treatment with the murine IL-4 Trap or the mouse IL-4 antibodyboth significantly antagonized the IL-4-mediated IgE increase in thismouse model (FIG. 37). This suggests that the murine IL-4 Trap bindsmurine IL-4 and antagonizes physiological responses elicited byendogenous IL-4 in vivo.

Example 17 Construction of Additional Single Chain IL-1 Traps

The techniques used to construct the DNA vectors described herein arestandard molecular biology techniques well known to the skilled artisan(see e.g., Sambrook et al. 1989 Molecular Cloning: A Laboratory Manual,Second Edition, Vols 1, 2, and 3, 1989; Current Protocols in MolecularBiology, Eds. Ausubel et al., Greene Publ. Assoc., Wiley Interscience,N.Y.). All DNA sequencing is done by standard techniques using an ABI373A DNA sequencer and Taq Dideoxy Terminator Cycle Sequencing Kit(Applied Biosystems, Inc., Foster City, Calif.).

a) IL-1 Trap 823 Sequence—The IL-1 Trap 823 sequence consists of theextracellular domain of human IL-1RAcP (corresponding to nucleotides1-1077 of SEQ ID NO: 39) followed by the extracellular domain of humanIL-1RI (corresponding to nucleotides 1078-2013 of SEQ ID NO: 39)followed by a part of the hinge region, the CH2 and CH3 domains of humanIgG1 (corresponding to nucleotides 2014-2703 of SEQ ID NO: 39)containing a mutation at nucleotides 2017-2019 (TGT->GGA) to change acysteine to a glycine. The nucleic acid sequence encodes the fusionpolypeptide sequence as set forth in SEQ ID NO: 40.

b) IL-1 Trap 823-1198-B Sequence—The IL-1 Trap 823-1198-B sequenceconsists of the extracellular domain of human IL-1RAcP (corresponding tonucleotides 1-1077 of SEQ ID NO: 41), followed by the extracellulardomain of human IL-1RI (corresponding to nucleotides 1078-2013 of SEQ IDNO: 41), followed by a stretch of amino acids (corresponding tonucleotides 2014-2019 of SEQ ID NO: 41), followed by the hinge region,the CH2 and CH3 domains of human IgG4 (corresponding to nucleotides2020-2709 of SEQ ID NO: 41). The nucleic acid sequence encodes thefusion polypeptide sequence as set forth in SEQ ID NO: 42.

c) IL-1 Trap 823-1267-C Sequence—The IL-1 Trap 823-1267-C sequenceconsists of the extracellular domain of human IL-1RAcP (corresponding tonucleotides 1-1077 of SEQ ID NO: 43), followed by the extracellulardomain of human IL-1RI (corresponding to nucleotides 1078-2013 of SEQ IDNO: 43), followed by a stretch of amino acids (corresponding tonucleotides 2014-2019 of SEQ ID NO: 43), followed by the hinge region,the CH2 and CH3 domains of human IgG4 (corresponding to nucleotides2020-2709 of SEQ ID NO: 43) containing a mutation at nucleotide 2047(T>C) to change a serine to a proline. The nucleic acid sequence encodesthe fusion polypeptide sequence as set forth in SEQ ID NO: 44.

d) IL-1 Trap 570-FE Sequence—The IL-1 Trap 570-FE sequence consists ofthe extracellular domain of human IL-1RI (corresponding to nucleotides 1to 996 of SEQ ID NO: 33), followed by the extracellular domain of humanIL-1RAcP (corresponding to nucleotides 997-2013 of SEQ ID NO: 33)followed by part of the hinge region, the CH2 and CH3 domains of humanIgG1 (corresponding to nucleotides 2014-2703 of SEQ ID NO: 33)containing a mutation at nucleotides 2017-2019 (TGT->GGA) to change acysteine to a glycine. The nucleic acid sequence encodes the fusionpolypeptide sequence as set forth in SEQ ID NO: 34.

e) IL-1 Trap 570-FE-B Sequence—The IL-1 Trap 570-FE-B sequence consistsof the extracellular domain of human IL-1RI (corresponding tonucleotides 1 to 996 of SEQ ID NO: 35), followed by the extracellulardomain of human IL-1RAcP (corresponding to nucleotides 997-2013 of SEQID NO: 35) followed by a stretch of amino acids (corresponding tonucleotides 2014-2019 of SEQ ID NO: 35) followed by the hinge region,the CH2 and CH3 domains of human IgG4 (corresponding to nucleotides2020-2709 of SEQ ID NO: 35). The nucleic acid sequence encodes thefusion polypeptide sequence as set forth in SEQ ID NO: 36.

f) IL-1 Trap 570-FE-C Sequence—The IL-1 Trap 570-FE-C sequence consistsof the extracellular domain of human IL-1RI (corresponding tonucleotides 1 to 996 of SEQ ID NO: 37), followed by the extracellulardomain of human IL-1RAcP (corresponding to nucleotides 997-2013 of SEQID NO: 37) followed by a stretch of amino acids (corresponding tonucleotides 2014-2019 of SEQ ID NO: 37) followed by the hinge region,the CH2 and CH3 domains of human IgG4 (corresponding to nucleotides2020-2709 of SEQ ID NO: 37) containing a mutation at nucleotide 2047(T>C) to change a serine to a proline. The nucleic acid sequence encodesthe fusion polypeptide sequence as set forth in SEQ ID NO: 38.

g) IL-1 Trap 1647-CtF Sequence—The IL-1 Trap 1647-CtF sequence consistsof the extracellular domain of human IL-1RII (corresponding tonucleotides 1-1044 of SEQ ID NO: 45) followed by the extracellulardomain of human IL-1RAcP (corresponding to nucleotides 1045-2058 of SEQID NO: 45) followed by a part of the hinge region, the CH2 and CH3domains of human IgG1 (corresponding to nucleotides 2059-2748 of SEQ IDNO: 45) containing a mutation at nucleotides 2062-2064 (TGT->GGA) tochange a cysteine to a glycine. The nucleic acid sequence encodes thefusion polypeptide sequence as set forth in SEQ ID NO: 46.

h) IL-1 Trap 1647-CtF-B Sequence—The IL-1 Trap 1647-CtF-B sequenceconsists of the extracellular domain of human IL-1RII (corresponding tonucleotides 1-1044 of SEQ ID NO: 47) followed by the extracellulardomain of human IL-1RAcP (corresponding to nucleotides 1045-2058 of SEQID NO: 47) followed by a stretch of amino acids (corresponding tonucleotides 2059-2064 of SEQ ID NO: 47) followed by the hinge region,the CH2 and CH3 domains of human IgG4 (corresponding to nucleotides2065-2754 of SEQ ID NO: 47). The nucleic acid sequence encodes thefusion polypeptide sequence as set forth in SEQ ID NO: 48.

i) IL-1 Trap 1647-CtF-C Sequence—The IL-1 Trap 1647-CtF-C sequenceconsists of the extracellular domain of human IL-1RII (corresponding tonucleotides 1-1044 of SEQ ID NO: 49) followed by the extracellulardomain of human IL-1RAcP (corresponding to nucleotides 1045-2058 of SEQID NO: 49) followed by a stretch of amino acids (corresponding tonucleotides 2059-2064 of SEQ ID NO: 49) followed by the hinge region,the CH2 and CH3 domains of human IgG4 (corresponding to nucleotides2065-2754 of SEQ ID NO: 49) containing a mutation at nucleotide 2092(T>C) to change a serine to a proline. The nucleic acid sequence encodesthe fusion polypeptide sequence as set forth in SEQ ID NO: 50.

j) IL-1 Trap 1649 Sequence—The IL-1 Trap 1649 sequence consists of theextracellular domain of human IL-1 RAcP (corresponding to nucleotides1-1074 of SEQ ID NO: 51) followed by the extracellular domain of humanIL-1RII (corresponding to nucleotides 1075-2058 of SEQ ID NO: 51)followed by a part of the hinge region, the CH2 and CH3 domains of humanIgG1 (corresponding to nucleotides 2059-2748 of SEQ ID NO: 51)containing a mutation at nucleotides 2062-2064 (TGT->GGA) to change acysteine to a glycine. The nucleic acid sequence encodes the fusionpolypeptide sequence as set forth in SEQ ID NO: 52.

k) IL-1 Trap 1649-B Sequence—The IL-1 Trap 1649-B sequence consists ofthe extracellular domain of human IL-1RAcP (corresponding to nucleotides1-1074 of SEQ ID NO:53) followed by the extracellular domain of humanIL-1RII (corresponding to nucleotides 1075-2058 of SEQ ID NO:53)followed by a stretch of amino acids (corresponding to nucleotides2059-2064) followed by the hinge region, the CH2 and CH3 domains ofhuman IgG4 (corresponding to nucleotides 2065-2754 of SEQ ID NO:53). Thenucleic acid sequence encodes the fusion polypeptide sequence as setforth in SEQ ID NO:54.

l) IL-1 Trap 1649-C Sequence—The IL-1 Trap 1649-C sequence consists ofthe extracellular domain of human IL-1RAcP (corresponding to nucleotides1-1074 of SEQ ID NO: 55) followed by the extracellular domain of humanIL-1RII (corresponding to nucleotides 1075-2058 of SEQ ID NO: 55)followed by a stretch of amino acids (corresponding to nucleotides2059-2064) followed by the hinge region, the CH2 and CH3 domains ofhuman IgG4 (corresponding to nucleotides 2065-2754 of SEQ ID NO: 55)containing a mutation at nucleotide 2092(T>C) to change a serine to aproline. The nucleic acid sequence encodes the fusion polypeptidesequence as set forth in SEQ ID NO: 56.

In addition to the sequences described supra and in the associatedfigures, the following modifications to those sequences are alsocontemplated by the subject invention. For IL1 Traps 823, 823-1198.B,and 823-1267.C:AcP alternative: A change at nucleotide 1043 from A to Cto change the amino acid from Lys to Thr. SG insertion: Betweennucleotides 1077 and 1078 an insertion of the nucleotides TCC GGA wouldadd a Ser Gly stretch of amino acids between the two receptor domains ofthe Trap. For IL1 Traps 570-FE, 570-FE.B, and 570-FE.C: AcP alternative:A change at nucleotide 1979 from A to C to change the amino acid fromLys to Thr. SG insertion: Between nucleotides 996 and 977 an insertionof the nucleotides TCC GGA would add a Ser Gly stretch of amino acidsbetween the two receptor domains of the Trap. For IL1 Traps1647-CtF,1647-CtF.B, and 1647-CtF.C: AcP alternative: A change at nucleotide 2027from A to C to change the amino acid from Lys to Thr. SG insertion:Between nucleotides 1044 and 1045 an insertion of the nucleotides TCCGGA would add a Ser Gly stretch of amino acids between the two receptordomains of the Trap. For IL1 Traps 1649, 1649-B, and 1649-C: AcPalternative: A change at nucleotide 1043 from A to C to change the aminoacid from Lys to Thr. SG insertion: Between nucleotides 1074 and 1075 aninsertion of the nucleotides TCC GGA would add a Ser Gly stretch ofamino acids between the two receptor domains of the Trap.

In addition, one of skill in the art will recognize that it may bedesirable to construct IL1 Traps in which the Fc domain is derived fromimmunoglobulins with different allotypes. None of the modificationsdescribed supra will alter the Trap's ability to bind IL1.

Example 18 Human IL-1 Trap Blocks the Effects of IL-1 in InflammedJoints

Background: Zymosan is a yeast cell wall extract that when injected intothe knee causes acute inflammation and upregulation of IL-1β in thejoint (Joosten et al. 1994 Clin Exp Immunol 97:204-211). Chondrocyteswill respond to the inflammation and local IL-1β by down regulatingproteoglycan synthesis, a feature of human arthritis that contributes tothe gradual destruction of cartilage in the joint (van den Berg et al.1982 Rheum Intl 1:165-169). Antagonists to IL-1β can be used to evaluatetheir ability to block the effects of zymosan-induced elevations inIL-1β.

Materials and Methods: Anesthetized male C57BL/6 mice (Taconic) weregiven an intra-articular (i.a.) injection of Zymosan A (Sigma; 300 μg in10 μl) into the right knee joint through the patellar ligament. SterilePBS was injected i.a. (10 μl) into the left knee joint through thepatellar ligament. Twenty four hours prior to i.a. injections, animalswere treated with either vehicle or hIL-1 Trap 569 (19 mg/kg, s.c.). Thepatellae were removed 24h after injection of zymosan in order to measureproteoglycan synthesis as described by van den Berg et al. 1982 supra.Briefly, each patella and associated ligament were incubated for 3 h at37° C., 5% CO₂ in media (RPMI with HEPES, HCO₃, glutamine &penicillin/streptomycin) containing 10 μCi/ml ³⁵S-sulfate (NEN DuPont).Following incubation, tissue was washed and fixed overnight in 10%formalin (VWR). The tissue was then placed in Decalcifing Solution (J.T. Baker) for 4 h prior to dissection of the patella from surroundingtissue. Each patella was then incubated overnight in Solvable (Packard)at 50° C. Ultima Gold liquid scintillation fluid (Packard) was added andthe samples were counted in a liquid scintillation counter. Values werereported as the ratio of cpm of zymosan patella/cpm of vehicle patellafor each animal.

Results: Intra-articular injection of zymosan reduces proteoglycansynthesis by approximately 50% relative to vehicle injection (FIG. 51).Administration of hIL-1 Trap prior to zymosan injection blocked thelocal action of IL-1β and proteoglycan synthesis returned toapproximately 90% of control. These data demonstrate that hIL-1 Trap 569can penetrate the joints after subcutaneous injection to effectivelyneutralize the biological effect of IL-1 within these joints.

Example 19 Murine IL-1 Trap Reduces the Severity of Arthritis Symptomsin Zymosan-Accelerated Collagen-Induced Arthritis (CIA) Model

Background. IL-1 has been implicated in the development of inflammationand cartilage destruction in rheumatoid arthritis (Dinarello 1996 Blood87(6):2095-2147; Wooley et al. 1993 Arthritis & Rheumatism 36(9):1305-1314). Collagen-induced arthritis (CIA) is a widely studied animalmodel of inflammatory polyarthritis with similarities to rheumatoidarthritis; common histopathological features include joint inflammationand erosion, synovial hyperplasia and inflammatory cell infiltration(Joe et al. 1999 Mol Med Today 5:367-369). Since previous studies haveshown that various anti-IL-1 treatments have a positive effect onreducing arthritis symptoms in CIA animals (van den Berg et al. 1994Clin Exp Immunol 95:237-243; Joosten et al. 1999 J Immunol163:5049-5055.; van de Loo 1992 J Rheumatol 19:348-356), Applicantsexamined the effect of a murine version of the IL-1 Trap (mIL-1 Trap) onthe progression of arthritis symptoms in this animal model. The humanversion of the IL-1 Trap is poorly cross-reactive with rodent IL-1. ThemIL-1 Trap consists of the extracellular domain of murine IL-1RAcP,followed by the extracellular domain of murine IL-1RI, followed by thehinge, CH2 and CH3 domain of murine IgG2a.

Male DBA-1 mice (Jackson Laboratories) were immunized intradermally atthe base of the tail with 100 μg/50 μl bovine Type II collagen (CII;Chondrex) emulsified with complete and incomplete Freund's adjuvant(2:1:1 ratio; Chondrex) and boosted intradermally with CII (100 μg/50μl) emulsified with incomplete Freund's adjuvant on day 21. Since CIA inDBA-1 mice occurs gradually over a long time period with a low incidence(Joosten et al. 1994 supra), Applicants synchronized the onset ofarthritis symptoms by injecting the animals intraperitoneally on day 30with 3 mg zymosan (Sigma). Two hours prior to zymosan injection, themice were randomly distributed into treatment groups and were injectedwith either vehicle or mIL-1 Trap (31 or 10 mg/kg, 3×/week, 8injections, s.c.). Arthritis symptoms (ASI scores, as described byWooley et al. 1993 supra) in the paws were evaluated 3×/week byindividuals who were blinded to the treatment groups. Animals weresacrificed 24 h after the 8th injection at which time paw width alongwith ASI scores were measured.

Results. Within 5 days after i.p injection of zymosan, vehicle treatedanimals had an significant increase in ASI score relative to thosereceiving mIL-1 Trap (FIG. 52) with symptoms reaching a maximum 10 to 14days after zymosan injection. Murine IL-1 Trap acted in a dose-dependentfashion such that animals receiving 10 mg/kg Trap had more arthritissymptoms (greater ASI score) than those receiving 31 mg/kg. However,both mIL-1 Trap-treated groups had a significantly lower degree ofarthritis symptoms than vehicle. This difference in ASI score is alsoreflected in the paw width at the time of sacrifice (FIG. 53). Animalsreceiving mIL-1 Trap had paw widths that were similar to those of naive,non-collagen immunized animals. These data indicate that mIL-1 Trap caneffectively neutralize IL-1 and block the development of arthriticjoints.

Example 20 IL-1 Trap 1649 Can Block the Activity of IL-1β

Various concentrations of IL-1 Trap 1649 were incubated in the presenceof 5 pM human IL-1b overnight at room temperature. The mixtures werethen added to duplicate wells of 293-NFkB cells (20,000 cells/well) for5 hrs at 37° C., 5% CO₂. 293-NFkB cells contain a stably integratedreporter plasmid possessing a luciferase gene driven by a promotercontaining 5 NFkB sites. Addition of IL-1b results in increasedluciferase gene expression. Steady-Glo Reagent (Promega) was added tothe cells for 15 min at room temperature and luciferase gene expressionwas quantitated as relative light units (RLU) by luminometry. IL-1 Trap1649 displays an IC₅₀ of 32 pM which indicates a Kd of ˜30 pM (see FIG.54). These data indicate that IL-1 Trap 1649 potently blocks IL-1.

The present invention is not to be limited in scope by the specificembodiments described herein. Indeed, various modifications of theinvention in addition to those described herein will become apparent tothose skilled in the art from the foregoing description and accompanyingfigures. Such modifications are intended to fall within the scope of theappended claims.

1. A recombinant nucleic acid molecule encoding a fusion polypeptidewhich forms a multimer capable of binding interleukin-1 (IL-1) to form anonfunctional complex, wherein the nucleic acid molecule comprises thenucleic acid sequence of SEQ ID NO:51.
 2. The nucleic acid of claim 1encoding a fusion polypeptide comprising the amino acid sequence of SEQID NO:52.
 3. A vector comprising the nucleic acid molecule of claim 1.4. A host-vector system for the production of a fusion polypeptide,comprising the vector of claim 3 in a suitable host cell.
 5. A method ofproducing a fusion polypeptide, comprising growing cells of thehost-vector system of claim 4, under conditions permitting production ofthe fusion polypeptide and recovering the fusion polypeptide soproduced.
 6. A recombinant nucleic acid molecule encoding a fusionpolypeptide which forms a multimer capable of binding interleukin-1(IL-1) to form a nonfunctional complex, wherein the nucleic acidmolecule comprises the nucleic acid sequence of SEQ ID NO:53.
 7. Thenucleic acid of claim 6 encoding a fusion polypeptide comprising theamino acid sequence of SEQ ID NO:54.
 8. A recombinant nucleic acidmolecule encoding a fusion polypeptide which forms a multimer capable ofbinding interleukin-1 (IL-1) to form a nonfunctional complex, whereinthe nucleic acid molecule comprises the nucleic acid sequence of SEQ IDNO:55.
 9. The nucleic acid of claim 8 encoding a fusion polypeptidecomprising the amino acid sequence of SEQ ID NO:56.
 10. A fusionpolypeptide comprising the amino acid sequence of SEQ ID NO:52.
 11. Acomposition comprising a multimer of the fusion polypeptide of claim 10.12. The composition of claim 11 wherein the multimer is a dimer.
 13. Amethod of treating arthritis, comprising administering a therapeuticallyeffective amount of the composition of claim 12.